Isochoric Heat Addition Engines and Methods

ABSTRACT

Engines and methods execute a high efficiency hybrid cycle, which is implemented in a volume within an engine. The cycle includes isochoric heat addition and over-expansion of the volume within the engine, wherein the volume is reduced in a compression portion of the cycle from a first quantity to a second quantity, the volume is held substantially constant at the second quantity during a heat addition portion of the cycle, and the volume is increased in an expansion portion of the cycle to a third quantity, the third quantity being larger than the first quantity.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application also claims priority to U.S. ProvisionalApplication Nos. 61/085,928, 61/149,889, 61/154,539 61/184,627, and61/219,495 filed respectively on Aug. 4, 2008, Feb. 4, 2009, Feb. 23,2009, Jun. 5, 2009, and Jun. 23, 2009. Each of the foregoingapplications is hereby incorporated herein by reference herein in itsentirety.

TECHNICAL FIELD

The present invention relates to internal combustion engines, and moreparticularly to internal combustion engines completing a high efficiencyhybrid cycle.

BACKGROUND ART

It is known in the prior art to run internal combustion engines oncycles such as a Diesel cycle, an Otto cycle, or an Atkinson cycle.These cycles all have distinct characteristics, but each hasdisadvantages that prevent them from achieving higher levels ofefficiency while maintaining high power outputs. Increasing theefficiency of engines designed to complete one of these cycles hasproven to be challenging. In a conventional engine part of the challengestems from the fact that all the processes such as compression,combustion and expansion, happen within the same space only at differenttimes. Additional challenges stem from an inability to create highcompression in the compression chamber and the inability to maintain thecompressed volume at a constant volume over an interval sufficient tooptimize combustion for various operating conditions or loads.Furthermore, with the exception of the Atkinson cycle, which is notcompleted in a typical combustion engine, efficiency is loss because theexpansion cycle is prematurely ended before the products of thecombustion process are exhausted and replaced with a fresh intake.

SUMMARY OF THE INVENTION

In a first embodiment, the invention provides a rotary engine. Thisembodiment includes a housing having an intake port and an exhaust port;a rotor rotatably mounted in the housing; and two gates. Each gate ismovably mounted with respect to the housing, so that each gate isengaged at least periodically with the rotor, wherein during engagementof at least one of the two gates with the rotor a volume is maintainedbetween a surface of the at least one gate, the rotor, and the housing.The volume exhibits a cycle during rotation of the rotor wherein thevolume is reduced in a compression portion of the cycle from a firstquantity to a second quantity, the volume is held substantially constantat the second quantity during a heat addition portion of the cycle, andthe volume is increased in an expansion portion of the cycle to a thirdquantity, the third quantity being larger than the first quantity.

In a related embodiment, the gates are slidably mounted with respect tothe housing. Alternatively, the gates are pivotally mounted with respectto the housing. In further embodiment, the pivotally mounted gates forman external wall of the housing. In another related embodiment, theengine further includes two cams coupled to the gates, the cams rotatedby a drive system synchronized with the rotation of the rotor.

In another embodiment, the invention provides a rotary engine. Theembodiment includes a housing having at least one intake port and atleast one exhaust port and a plurality of rotors rotatably mounted inthe housing. Each rotor is coupled to one of the at least one intakeport or to one of the at least one exhaust port. The embodiment alsoincludes a plurality of gates, each gate associated with, and in contactwith, one of the rotors; and at least one combustion chamber. Each ofthe at least one combustion chamber is in communication with each rotorof a pair of the rotors. A first rotor of the pair of rotors is coupledto one of the at least one intake port and a second rotor of the pair ofrotors is coupled to one of the at least one exhaust port. The first andsecond rotors move synchronously, wherein (i) the first rotor and itsgate define in relation to the housing a compression volume exhibiting acompression portion of an engine cycle during rotation of the firstrotor, by which a compressed volume of air is periodically coupled tothe first rotor's corresponding combustion chamber and (ii) the secondrotor and its gate define in relation to the housing an expansion volumeexhibiting an expansion portion of an engine cycle during rotation ofthe second rotor, by which a combusted mixture in the first rotor'scombustion chamber is periodically coupled to the expansion volume, andwherein the compression volume is reduced in the compression portion ofthe cycle from a first quantity to a second quantity, a volume in whichcombustion occurs is held substantially constant at the second quantityduring a heat addition portion of the cycle, and the expansion volume isincreased in the expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.

In yet another embodiment there is provided a rotary engine. Theembodiment includes a housing having an intake port and an exhaust portand an interior surface having a first arcuate segment characterized bya constant radius of curvature and a second arcuate segmentcharacterized by a shape different from that of the first segment. Theembodiment also includes a rotor rotatably mounted concentrically withinthe first segment of the housing, and disposed concentrically around aC-cam having a constant radius cylindrical surface except where it has arecess. The embodiment further includes at least one compression vanemovably mounted in the rotor for contacting the C-cam and defining acompression volume with the rotor, the C-cam, and the housing.Similarly, the embodiment further includes at least one expansion vanemovably mounted in the rotor for contacting the interior surface of thehousing and defining an expansion volume with the rotor and the housing.It also includes a combustion chamber, disposed in the rotor, associatedwith the at least one compression vane and the at least one expansionvane, wherein (i) the compression volume exhibits a compression cycleduring rotation of rotor, by which a compressed volume of a workingmedium is periodically coupled to the combustion chamber and (ii) theexpansion volume exhibits an expansion cycle during rotation of therotor, by which combustion products in the combustion chamber areperiodically coupled to the expansion volume.

In a related embodiment, the engine further includes a plurality ofcompression vanes, a plurality of expansion vanes, and a plurality ofcombustion chambers, each of the combustion chambers being associatedwith a corresponding compression vane and a corresponding expansionvane. Alternatively or in addition, the at least one compression vaneand the at least one expansion vane are mounted in the rotor by one of apivotal mount and a slidable mount. Alternatively or in addition, theembodiment further includes a plurality of C-rings mounted in the rotorto provide sealing between the rotor and the housing. Optionally, theembodiment further includes a plurality of grooves formed within thehousing for guiding motion of the vanes.

In another embodiment, the invention provides an internal combustionengine including a bilateral piston, having an intake port and anexhaust port, and pair of opposed piston faces; and a housing, mountedconcentrically outside of the piston and having a pair of opposedinternal contact faces. The housing moves in reciprocal motion relativeto the piston, along a longitudinal axis, each contact face coming intoproximity of a corresponding one of the piston faces of the piston at alimit of the reciprocal motion. The embodiment includes a pistonactuator engaged with the piston relative to the housing. The pistonactuator controls the motion of the housing with respect to the pistonso that a volume is defined between each piston face and a correspondingone of the contact faces. The volume exhibits a cycle duringreciprocation of the housing relative to the piston wherein the volumeis reduced in a compression portion of the cycle from a first quantityto a second quantity, the volume is held substantially constant at thesecond quantity during a heat addition portion of the cycle, and thevolume is increased in an expansion portion of the cycle to a thirdquantity, the third quantity being larger than the first quantity.

In a related embodiment, the piston actuator is a cam having a shapethat provides a dwell to the reciprocating motion of the housingrelative to the piston. Alternatively, the piston actuator is anelectromagnetic coil system. Alternatively or in addition, the pistonand the housing are cylindrically shaped.

In yet another embodiment, the invention provides an internal combustionengine and the embodiment includes a cylinder having an intake port andan exhaust port and a pair of pistons disposed for coordinatedreciprocating motion in the cylinder. Each of the pistons has a pistonface. The pistons are coupled to a rotational output in a manner tocause the pistons to define, within the cylinder and between the pistonfaces, a volume. The volume exhibits a cycle during reciprocation of thepistons wherein the volume is reduced in a compression portion of thecycle from a first quantity to a second quantity, the volume is heldsubstantially constant at the second quantity during a heat additionportion of the cycle, and the volume is increased in an expansionportion of the cycle to a third quantity, the third quantity beinglarger than the first quantity.

In yet another embodiment, the invention provides an internal combustionengine, and the embodiment includes a housing having an intake port andan exhaust port; at least one piston movably mounted with respect to thehousing; and means for moving the piston through a cycle so that avolume is maintained between the piston and the housing. The volumeexhibits a cycle during movement of the piston wherein the volume isreduced in a compression portion of the cycle from a first quantity to asecond quantity, the volume is held substantially constant at the secondquantity during a heat addition portion of the cycle, and the volume isincreased in an expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.

In a further related embodiment, the piston includes a liquid.

In yet another embodiment, the invention provides an internal combustionengine, and the embodiment includes a housing having an intake port andan exhaust port; and a low pressure chamber and a high pressure chamberdisposed in the housing. The low pressure chamber is larger than thehigh pressure chamber. Each chamber has an epitrochoid-shaped interiorin which is disposed a three-apex rotor, rotationally mounted to moveeccentrically within the corresponding chamber, to establish threecavities, which over an engine cycle, handle the functions of intake,compression, intermediate, and expansion, three of such functions beingoperative at any given time in each chamber; wherein (i) the cavityhandling compression in the low pressure chamber is coupled to thecavity handling intake in the high pressure chamber; (ii) the cavityhandling expansion in the high pressure chamber is coupled to the cavityhandling expansion in the low pressure chamber; and (iii) the cavity inthe high pressure chamber handling the intermediate function handlesheat addition so as to produce combustion therein.

In yet another embodiment, the invention provides a rotary engine, andthe embodiment includes an inner rotor, the inner rotor having aplurality N of lobes, and a receiving member, the inner rotorrotationally moving about an axis that is displaced relative to an axisof the receiving member, the receiving member having N+1 recesses formating with successive lobes as the inner rotor rotates. The embodimentalso includes a drive for causing rotation of the inner rotor relativeto the receiving member, so that a volume is defined with respect toeach lobe of the inner rotor and a corresponding recess of the receivingmember. The volume exhibits a cycle wherein the volume is reduced in acompression portion of the cycle from a first quantity to a secondquantity, the volume is held substantially constant at the secondquantity during a heat addition portion of the cycle, and the volume isincreased in an expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.

A further related embodiment further includes a housing, the housinghaving and intake port and an exhaust port, wherein the inner rotorrotates in a first direction relative to the housing and the receivingmember rotates in a second direction relative to the housing. In anotherrelated embodiment, the receiving member is part of the housing, thehousing having an intake port and exhaust port.

Another embodiment provides a system for sealing a rotor of an internalcombustion engine in relation to a housing, the rotor having an edge anda face. The system of this embodiment includes a groove formed in theface of the rotor, proximate to the edge and having a radially inwardwall and a radially outward wall, the groove having a bevel located inthe radially outward wall; and a sealing strip disposed in the grove andhaving, in contact with the groove, a conformal surface. The strip isengaged in frictional contact against the housing, the housingpresenting to the sealing strip a substantially flat surface, thefriction tending to cause the strip to rotate slightly with respect tothe rotor and to move slightly axially in a direction out of the groove,so as to reduce any gap between the strip and the housing and so as toincrease sealing between the rotor and the housing.

In another embodiment, the invention provides a rotary engine, and theembodiment includes a housing having an intake port and an exhaust port;a rotor rotatably mounted in the housing; and an annular segment of ahollow cylinder, mounted and driven to pivot in oscillatory fashionabout a central axis. The segment has first and second opposed endsforming a pair of connected gates, each end periodically contacting therotor, so as to define a volume within the housing. The volume exhibitsa cycle during rotation of the rotor wherein, (i) while only the firstend contacts the rotor, the volume is reduced in a compression portionof the cycle from a first quantity to a second quantity, (ii) the volumeis held substantially constant at the second quantity during a heataddition portion of the cycle, and (iii) while only the second endcontacts the rotor, the volume is increased in an expansion portion ofthe cycle to a third quantity, the third quantity being larger than thefirst quantity.

In another embodiment, the invention provides an internal combustionengine, and the embodiment includes a housing having an intake port andan exhaust port; at least three pistons movably mounted with respect tothe housing, each piston formed of magnetic material; and a series ofelectromagnetic coils disposed around the housing. The electromagneticcoils are electronically controlled to exert forces on the pistons so asto implement a cycle wherein a volume is maintained between the pistonsand the housing. The volume exhibits a cycle during movement of thepistons wherein the volume is reduced in a compression portion of thecycle from a first quantity to a second quantity, the volume is heldsubstantially constant at the second quantity during a heat additionportion of the cycle, and the volume is increased in an expansionportion of the cycle to a third quantity, the third quantity beinglarger than the first quantity.

In another embodiment, the present invention provides a sealing systemfor a rotary engine, and the embodiment includes a plurality of groovesformed in an interior surface of a housing wall, and a spring-loadedsealing strip disposed in each of the grooves; an orifice in the housingwall located between the grooves, the orifice coupled to an oil supply;and a floating cover disposed between the housing wall and a rotor ofthe engine. The floating cover has an inner face adjacent to a face ofthe rotor and an outer face adjacent to the interior surface of thehousing wall. The inner face of the floating cover includes a groovehaving a diameter conforming generally to a diameter of the rotor, and aspring- loaded sealing strip located in the grove of the floating cover.The oil supply causes pressurized oil to apply an axial force to theouter face of the floating cover in opposition to axial forces on theinner face of the floating cover caused by a working medium of theengine so as to assist in sealing the engine.

In another embodiment, the invention provides an apex sealing system ina rotary engine for a first member that is one of a gate or a vane inrelation to a second member, moving in relation to the first member andat least periodically in contact therewith at a contact region of thefirst member. The apex sealing system includes a recess formed in thecontact region of the first member; and a roller rotationally mounted inthe recess, so that the roller contacts the second member when the firstmember is in contact with the second member.

In another embodiment, the invention provides a sealing system forsealing, in a rotary engine, an interface between a first member andsecond member with respect to which the first member moves, the firstmember presenting an edge, parallel to an axis, and in contact with thesecond member. The sealing system of this embodiment includes at leastone recess formed in the edge; and a plurality of axially adjacentstrips, mounted in the at least one recess, each strip being springloaded, to maintain the strips in engagement with the second member.

In an another embodiment, the invention provides a rotary engine, andthe embodiment includes a housing having an intake port and an exhaustport; a rotor rotatably mounted in the housing, the rotor having anaxial channel formed in an edge of the rotor, so that the channel liesaxially between two integrally formed end plates; and at least one gatemovably mounted with respect to the housing so as to be engageable withthe axial channel and having a shape conformal with the shape of theaxial channel. During engagement of at least one gate with the rotor avolume is maintained between a surface of the at least one gate, therotor, and the housing. The volume exhibits a cycle during rotation ofthe rotor wherein the volume is reduced in a compression portion of thecycle from a first quantity to a second quantity, the volume is heldsubstantially constant at the second quantity during a heat additionportion of the cycle, and the volume is increased in an expansionportion of the cycle to a third quantity, the third quantity beinglarger than the first quantity.

In yet another embodiment, the invention provides a sealing system forimproving sealing in a rotary engine between a first member thatfunctions as one of a vane or gate, and capable of motion along an axis,and a second member moving with respect to the first member, the firstmember engageable against the second member at a limit of motion alongthe axis. The sealing system of this embodiment includes a matched pairof components, the matched pair serving as the first member. Each one ofthe matched pair is mounted so as to be separately movable along theaxis of movement of the first member, so that each component may movedifferentially relative to the other component to improve sealing at thelimit of motion of the components.

In yet another embodiment, the invention provides a rotor face seal, andthe embodiment includes radial features such as ridges, dimples, stripsradiated in a radial direction and disposed on a flat surface of therotor; these features reduce tangential flow of the fluid across theflat face surface of the rotor.

In further related embodiment, there is provided a method of operatingan HEHC engine in a manner permitting adjustment of power output, themethod of this embodiment includes, in the heat addition portion of thecycle, adding fuel to the volume and causing combustion of the fuel, theamount of fuel added, when fuel is added, being substantially constantover all cycles, so as to produce maximum power over each cycle whenfuel is added; and controlling addition of fuel to occur only over asufficient number of cycles per unit of time in order to produce adesired power output of the engine, and, for each cycle wherein additionof fuel is withheld, supplying heat during the heat addition portion ofthe cycle by heat transfer from at least one of (i) walls of the enginedirectly and (ii) a heat exchanger. In a further related embodiment, theHEHC engine is any of the engine embodiments described above.

Yet another embodiment provides an improved rotary internal combustionengine of the homogenous charge compression ignition type, causingcombustion of a fuel- air mixture when a state of the mixture istransformed from subcritical to critical. The improvement includes acatalytic surface carried on a mechanical substrate, the surface beingnormally concealed from the mixture; and a trigger for initiatingcombustion by causing the catalytic surface to be exposed to the mixturewhen the mixture is placed under minimum volume conditions. In a furtherrelated embodiment, the trigger includes a catalytic surface placeddirectly on a rotor of the engine, in such a manner that it is exposedeach time the rotor reaches a specific angular extent in the cycle.Alternatively or in addition, the trigger includes a catalytic surfaceplaced in a location of a housing of the engine, in such a manner thatit is exposed each time the rotor reaches a specific angular extent inthe cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features of the invention will be more readily understoodby reference to the following detailed description, taken with referenceto the accompanying drawings, in which:

FIG. 1 is a graph illustrating a high efficiency hybrid cycle inaccordance with an embodiment of the present invention in comparison toan Otto and Diesel cycle.

FIG. 2 is a graph illustrating a high efficiency hybrid cycleimplementing a scavenging method in accordance with an embodiment of thepresent invention.

FIG. 3 a-3 c illustrate a rotary engine with 2 straight gates inaccordance with an embodiment of the present invention.

FIGS. 4 and 5 illustrate the engine of FIG. 3 during different portionsof the high efficiency hybrid cycle.

FIG. 6 illustrates a rotary engine with 2 straight gates in accordancewith another embodiment of the present invention.

FIG. 7 illustrates a rotary engine with 2 straight gates in accordancewith another embodiment of the present invention.

FIG. 8 illustrates a rotary engine with 2 pivoting gates in accordancewith an embodiment of the present invention.

FIG. 9 illustrate the engine embodiment of FIG. 8 during differentportions of the high efficiency hybrid cycle.

FIG. 10 illustrates a rotary engine with 2 pivoting gates that form apart of the housing in accordance with another embodiment of the presentinvention.

FIG. 11 illustrates a rotary engine with 2 pivoting gates that may beused with a cycle incorporating the scavenging process in accordancewith an embodiment of the present invention.

FIG. 12 illustrates a rotary engine with a rotor and a pivoting gate inaccordance with an embodiment of the present invention.

FIG. 13 shows an engine with 2 rotors and 2 gates in accordance with anembodiment of the present invention.

FIG. 14 shows an engine with a plurality of rotors and gates inaccordance with an embodiment of the present invention.

FIG. 15 shows an embodiment of the present invention having two rotorswith multiple gates.

FIG. 16 shows the operational sequence of an engine depicted in FIG. 15.

FIG. 17 shows an exploded view of an engine with multiple sets ofpivoting gates in accordance with an embodiment of the presentinvention.

FIGS. 18 a and 18 b show a perspective view and cross sectional view ofthe engine depicted in FIG. 17.

FIGS. 19 a-19 d show the engine embodiment of FIG. 17 during differentportions of the high efficiency hybrid cycle.

FIGS. 20 a-20 c provides magnified details of elements of the enginedemonstrated in FIG. 15.

FIG. 21 shows an engine having a single rotor and multiple vanes.

FIG. 22 illustrates a bilateral piston engine in accordance with anembodiment of the present invention.

FIG. 23 illustrates a bilateral piston engine in accordance with anotherembodiment of the present invention.

FIG. 24 illustrates a multiple piston engine in accordance with anotherembodiment of the present invention.

FIG. 25 illustrates an engine with a gate drive and multiple pistons inaccordance with an embodiment of the present invention.

FIG. 26 illustrates an engine having dual gates and multiple pistons inaccordance with an embodiment of the present invention.

FIG. 27 illustrates a dual piston eccentric drive engine in accordancewith an embodiment of the present invention.

FIGS. 28-32 illustrates an opposed piston engine in accordance with anembodiment of the present invention.

FIG. 33 illustrates a dual rotor internal combustion engine inaccordance with an embodiment of the present invention.

FIGS. 34 a-34 e illustrate the dual rotor engine of FIG. 30 throughoutdifferent portions of a cycle.

FIG. 35 illustrates another dual rotor engine in accordance with anembodiment of the present invention.

FIG. 36 illustrates an eccentric single vane engine in accordance withan embodiment of the present invention.

FIG. 37 illustrates a fuel delivery system in accordance withembodiments of the present invention.

FIG. 38 illustrates a catalyst used as a homogenous charge compressionignition trigger (HCCI) in accordance with an embodiment of the presentinvention.

FIG. 39 illustrates a catalyst coated rotor for use with an embodimentof the present invention.

FIGS. 40 a-40 e illustrate various face seals in accordance withembodiments of the present invention.

FIG. 41 illustrates a floating cover seal design in accordance with anembodiment of the present invention.

FIG. 42 depicts an integrated rotor engine in accordance withembodiments of the present invention.

FIGS. 43 a-43 f show various rotor sealing mechanisms in accordance withembodiments of the present invention.

FIGS. 44 a-44 b shows roller and apex seals for use with embodiments ofthe present invention.

FIG. 45 illustrates split faces seals in accordance with embodiments ofthe present invention.

FIG. 46 illustrates dual vane sealing in accordance with an embodimentof the present invention.

FIG. 47 illustrates face and apex seals in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Definitions. As used in this description and the accompanying claims,the following terms shall have the meanings indicated, unless thecontext otherwise requires:

A “rotor” is a structure, rotatably mounted in a housing that transmitstorque, developed as a result of combustion, to a mechanical output.

A “gate” is a movable structure, for partitioning a volume, that isperiodically or continuously in contact with a member, such as a rotor,that is moving with respect thereto. A gate may move with a rotating ortranslating motion, and such motion need not substantially change thevolume of a relevant cavity.

A “vane” is a movable structure, motion of which causes displacement ofa volume, that also has a partitioning function and is periodically orcontinuously in contact with a member, such as a rotor or a housing thatis moving with respect thereto.

A “piston” is a mass moving linearly with respect to a housing in whichit is located and that transmits force relative to the housing,developed as a result of combustion, directly or indirectly to amechanical output. “Linear” motion here includes motion along a paththat may be straight or curved.

A “sealing system” is an arrangement for reducing a gap between twomating parts that are movably mounted with respect to one another. Sucha gap may be attributable, among other things, to limitations ofmanufacturing tolerances as well as to differences in thermal expansionexperienced by the mating parts.

A prismatic surface is a surface generated by all the lines that areparallel to a given line and intersect a broken line that is not in thesame plane as the given line. The broken line is the directrix of thesurface; the parallel lines are its generators (or elements). If thebroken line is close (i.e. a closed polygon), then the surface is aclosed prismatic surface.

For the sake of the foregoing discussion the following terms with theircorresponding definitions will be used:

A/F—Air/Fuel

Air Knife—an air blown by the fan through the scavenging chamber orthrough inlet and outlet ports, located opposite to each other or undersome angle to each other.

Chambers:

-   -   a. CbC—Combustion Chamber    -   b. CmC—Compression Chamber    -   c. EpC—Expansion Chamber    -   d. EhC—Exhaust Chamber

Chambers—the Space between various components of the engine filled withWorking Medium

CV CbC—Constant Volume Combustion Chamber

EGR—Exhaust Gas Recirculation

Gates:

-   -   a. Compressor Gate; also called C-Gate.    -   b. Expander Gate; also called E-Gate

HEHC—High Efficiency Hybrid Cycle

HCHC—Homogeneous Charge Hybrid Cycle

HEHC-S—High Efficiency Hybrid Cycle (in Scavenging mode)

HCHC-S—Homogeneous Charge Hybrid Cycle (in Scavenging mode)

Heat Addition—heat may be added by combusting the fuel in the air or bya heat exchange process with a heat exchanger located within theconstant volume combustion chamber or just with the walls of the engine(primarily combustion chamber walls)

FI—Fuel Injector

V_(CbC)—Combustion Chamber Volume

WM—Working Medium—Air or Air/Fuel Mixture or combusted gasses

In this application, several different engine embodiments are disclosed.These engine embodiments describe engines which are capable of operatingat very high maximum efficiency (˜57% or above), very high maximumaverage efficiency (above ˜50%), very high power density and specificpower, low vibration levels, low sound levels, and low emissions levels.

To understand the design intent and for completeness sake, we willreiterate the basic thermodynamic principles behind the high efficiencyhybrid cycle, which are illustrated in FIG. 1. The basic premise of thecycle show in figures comprises the following cycle portions: (1)compression of air only to high compression ratio (similar to Dieselcycle engines), (2) heat addition (by combustion of fuel or externally)at constant volume conditions (similar to Otto cycle engines), and (3)expansion to atmospheric pressure (similar to Atkinson or Miller cyclesengines). Because this engine completes a cycle wherein heat is added ata constant volume, during which the pressure increases the engine may becharacterized as an isochoric heat addition engine.

An engine capable of operating in a regime of isochoric heat additionand over-expansion consists of stationary and movable parts. Stationaryparts are sometimes herein referred to as the housing. Movable parts mayinclude one or more of the following structures: rotors, pistons, gates,and vanes. The movable parts generally separate a cavity during at leastsome portion of a cycle, wherein a cavity includes a void formed betweena stationary housing and movable components. A cavity is filled with aworking medium during the cycle. A change in the cavity volume duringthe operation of the engine is the manifestation of the compression orexpansion of the working medium.

During operation of an engine in accordance with an embodiment of thepresent invention, a cavity formed between the stationary housing and amoving component is filled with a working medium. This working medium(WM) undergoes cyclical transformations during operation of the engine.In a first stage the cavity is contracted from its initial volume V₁ toa minimal volume V₂. During this step the cavity will be called thecompression chamber (CmC), having an initial volume V_(i). In a secondstage the cavity remains substantially constant at V₂ for a finite timeperiod of time. During this stage the cavity will be called thecombustion chamber (CbC), having a constant volume V₂. Subsequently thecavity will expand to a volume V₄, so that V₄≧V₁≧V₂. During this stagethe cavity will be called an expansion chamber (EpC), having a finalvolume V₄.

Heat could be added to the working medium while the volume of thiscavity is at V2≦V≦V₁. Work on the working medium is exerted during thephase of operation when the volume is contracted from V₁ to V₂. No workis exerted or extracted on or from the working medium, except perhaps toovercome small frictional losses, during the phase of operation when thevolume of the cavity remains substantially constant at V₂. Work isextracted from the working medium during the phase of operation when thevolume is expanding from V₂ to V₄.

The net work produced by the cycle is the difference between extractedwork and exerted work, also taking into account the losses due to thefriction in the system. If heat is added by means of combusting fuel,the engine constitutes an internal combustion engine. If heat is addedby external means, such as via heat pipe or directly heating the housingwalls, etc., the engine is an external combustion engine.

In this application several embodiments are disclosed that includevarious housing configurations and different movable parts. Theembodiments disclosed are all capable of executing the high efficiencyhybrid cycle disclosed herein in addition to other standard cycles, suchas Diesel, Otto, HCCI, etc.

Various engines embodiments of the present invention will operate in aconventional Otto cycle with spark ignition, in a conventional Dieselmode with fuel injection, or in HCCI mode.

In analogy with conventional piston engines the high efficiency hybridcycle (HEHC) and the homogeneous charge hybrid cycle (HCHC) may becalled 4-stroke cycles as they have 4 distinctive strokes: Intake,Compression, Combustion & Expansion, and Exhaust. A scavenging variantof either of these cycles is equivalent to a 2-stroke engine cyclewherein, at the end of expansion, the cavity is scavenged by the blow-byambient air, which removes combusted gasses and refills the cavity witha fresh air or an air/fuel mixture charge.

As indicated, the HEHC pressure-volume diagram is shown in FIGS. 1 and2. In the initial state, only the air is compressed, like in Dieselcycle, during the compression stroke. Fuel may be added close to the endof compression stroke or just after the compression stroke. Since air isalready compressed at this point to a relatively high pressure (˜55bar), high injection pressures, similar to those used in modern dieselengines are required to achieve full combustion and clean exhausts. Theoperation is akin to Diesel engines except for the fact that combustionoccurs at the constant volume, as achieved in Otto cycle engines thatare spark ignited. However, unlike spark ignition engines, thecombustion occurs due to fuel injection into a very hot compressed air.Having said this, however, a spark plug may be used as well. Expansionoccurs in this cycle to ambient pressures, similar to Atkinson cycle.

Partial load operation may be accomplished by fuel modulation, as inDiesel engines or by skipping some of the injections all together, as itwill be described below.

Due to similarities of this cycle to Diesel, Otto and Atkinson, thiscycle is referred to as a “Hybrid Cycle”. It may also possible to injectwater during combustion and/or expansion strokes as this may improve theefficiency of the engine, while providing for cooling from within theengine.

If leakage between moving components and housing is kept at low level,the maximum efficiency of this cycle is expected to be about 57%, whileaverage efficiency is expected to be above 50%.

From a design point of view, implementation of such a cycle will requireexistence of constant volume combustion chamber over a finite timeperiod and expansion chamber volume larger than intake volume.Additionally, intake and exhaust strokes may be eliminated if scavenging(air blow trough during intake/exhaust) is used as shown in FIG. 2

The homogeneous charge hybrid cycle (HCHC) is a modification of theHEHC, in which a lean air/fuel mixture, formed during intake and/orcompression strokes, is being compressed as opposed to the compressionof only air. When the mixture reaches temperatures sufficient forauto-ignition at the end of compression stroke, a spontaneous combustionoccurs. Compared to HEHC, the HCHC is characterized by slightly lowercompression ratio and, therefore, exhibits a lower efficiency.

The HCHC cycle may also be compared with a conventional HomogeneousCharge Compression Ignition (HCCI), which will occur when temperature ofair/fuel mixture reaches the auto-ignition point, which, if engine isproperly designed, should occur exactly at, or just prior to, the end ofcompression. The ignition in an HCCI cycle is almost instantaneousthroughout the whole volume occurring without flame propagation or shockwave and at lower temperatures (which is a good thing for emissions andengine integrity) but, albeit, at a lower pressures, which leads tolower efficiencies lower than those achieved during an HEHC.

For a given air inlet temperature, pressure, the amount of Exhaust GasRecirculation (EGR), air humidity, etc. there exists a critical ratio ofair to fuel (lambda) under which spontaneous combustion will occur whentemperature of compressing mixture reaches the auto-ignition point atthe end of compression. For the sake of further discussion, we definethis set of conditions as “critical conditions”. If for example, theinlet temperature is too cold, and all other parameters are the same,then when air/fuel mixture reaches the target compression ratio, nocombustion will occur. Conversely, if all the parameters are critical,but air/fuel mixture is too lean, then no combustion will occur either.Such conditions may be referred to as “sub-critical”.

In conventional HCCI engines, a very narrow time window exists whenauto-ignition may occur and this presents very challenging problems forengine control during part load conditions. That is why conventionalHCCI engines are still in research stage for the last 25 years. In Ottoengines the sparks play a role of combustion trigger. In Diesel engines,the start of the fuel injection is a trigger. In classical HCCI, thereexists no trigger, which is why the combustion process is very difficultto control. If ignition occurs before top dead center (TDC), thecombustion gas forces acting upon full face of the piston will bedirected against the motion of the piston and will not only slow theengine and greatly reduce the efficiency, but will eventually destroythe engine. If ignition occurs after TDC the efficiency will besignificantly reduced. The longer the delay, the lower the efficiency.

Since combustion is almost instantaneous, the constant volume combustionchamber is not strictly speaking required from efficiency standpoint,but is critical from the control point of view as it creates ratherlarge window for combustion to occur. The HCHC cycle is superior to theconventional HCCI cycle due to several reasons. One reason includes thefact that it has a larger expansion volume than intake volume, whichleads to a higher efficiency. The fuel in both HCCI and HCHC engines maybe injected together with air into the intake port by low-pressure fuelinjector or carburetor. In addition to this, a second fuel injectioncould be performed right before the auto-ignition conditions arereached. This additional injection will have only minor effect onautoignition timing due to combustion delay, but would allow control atpart-load conditions and result in increase in efficiency. Theadditional fuel will not have sufficient time to undergo throughhomogenization process and this fuel will represent small clusterssuspended in or moving through the original homogeneous air/fuel mix.The original mix or slightly sub-critical mix will auto-ignite as in thecase of HCCI above, while additional fuel will quickly evaporate andprovide for secondary combustion. The degree of “sub-criticality” forthe most efficient burn has to be determined analytically andexperimentally. By the way, such an additional fuel injection is alsopossible in conventional HCCI. While it is possible to use both thecarburetor and fuel injector (FI), since both of them provide verysimilar functionality, it is probable that only one will be used in theengine. To control the part-load operation by shutting off the fuelsupply, it would be preferable to use FI. If carburetor is being used,it should be run at full throttle to avoid throttling losses, so onlyneedle valve supplying the specific amount of fuel might need to becontrolled.

Having a constant volume combustion chamber (CV CbC) allows largeoperating time window for auto ignition to occur. This is due to thefact that auto ignition can occur any time after CV CbC is created(which is equivalent to TDC point of conventional engines).

The timing of ignition event in some embodiments, while important is notcritical: if auto-ignition occurs slightly before the end of compressionstroke (a point that could be compared with TDC), the differential forceon the moving element (i.e. Rotor) of the engine will be very small, dueto the small size of the CbC “throat” or exit cross section. Anyoccurrence of auto-ignition after the “TDC” is ok as well since it willoccur within the CV CbC, i.e. at the time when forces acting upon themoving element (i.e. Rotor) will act in radial direction only and willbe fully absorbed by the bearings—i.e. they will not impede the motion.

It is also a relatively easy to introduce a “trigger” into the system,due to existence of CV CbC, by exposing the CbC to catalytic substance.The combustion will occur due to stimulated ignition which could beaccomplished by various means described in patent applicationPCT/US07/74980, incorporated herein by reference. One simple way ofaccomplishing this is by the deposition of catalyst, such as Nickel,onto one of the surfaces that makes CV CbC in such a way that whenchamber containing the compressed air/fuel mixture in slightly“sub-critical” condition enters the segment containing thecatalyst—reaction will be triggered by such a catalyst. This catalyticsegment may be extended into the expansion zone if burning is expectedto continue in this zone (though this is undesirable from efficiencystandpoint), see FIG. 39.

The term “Scavenged” is borrowed herein from conventional 2-cyclecompression or spark ignition engines: the air is blown through thecylinder at the end of expansion stroke and combusted air is replacedwith a fresh charge. The same notion may be applied to engine operatingunder the HEHC or HCHC, if we will blow the air trough the chamber atthe end of expansion stroke. Thus, the exhaust chamber and the intakechamber can be replaced by scavenging chamber.

Scavenging may be accomplished by an “Air Knife”—an air blown by the fanthrough the scavenging chamber or through inlet and outlet ports,located opposite to each other or under some angle to each other.

The benefit of this mode is increase in power density, as one of thechambers is eliminated. This may be especially beneficial if externalengine cooling is required as scavenging may be combined with cooling.

The deficiency is slight reduction in efficiency as energy is requiredto scavenge the air.

A qualitative comparison of theoretical efficiencies is shown in FIG. 1a). A quantitative comparison of ideal cycles, which calculates themaximal theoretical efficiency, is shown in FIG. 1 b), which wascomputed on the basis of below expressions for HEHC, Diesel and OttoCycles:

$\eta_{th}^{HEHC} = {{1 - {k\frac{T_{4} - T_{1}}{T_{3} - T_{2}}}} = {1 - {k\frac{r_{E} - r_{C}}{r_{E}^{k} - r_{C}^{k}}}}}$$\eta_{th}^{Diezel} = {{1 - {\left( \frac{1}{k} \right)\frac{T_{4} - T_{1}}{T_{3} - T_{2}}}} = {1 - {\left( \frac{1}{k} \right)\frac{r_{E}^{- k} - r_{C}^{- k}}{r_{E}^{- 1} - r_{C}^{- 1}}}}}$$\eta_{th}^{Otto} = {{1 - \frac{T_{4} - T_{1}}{T_{3} - T_{2}}} = {1 - \frac{1}{R_{C}^{k - 1}}}}$

Here, k=1.3; r_(C)—compression ratio; r_(E)—expansion ratio; T₁ throughT₄ are temperatures of WM through various points in a cycle. See alsopoints defined in a FIG. 1 a.

Operation at full load is transparent and the maximal amount of fuel isinjected by one of the means described above. To operate at part load,especially with heavy fuels like Diesel, JP8, etc., a number of optionsare available. The amount of fuel may be modulated as in as inconventional engines. The engine may be run lean, i.e. inject less thenstoichiometric amount of fuel and run in HCHC mode. The amount of EGRmay be varied, as in conventional HCCI engines. Alternatively, andpreferably, the engine may be run in “digital mode”—by running everycycle at full load, but skipping cycles once and a while. For example,skipping three out of each ten cycles would enable us to run under ˜70%of full power; skipping eight out of each ten cycles will enable us torun under ˜20% loan, etc.

The cycle skipping can be implemented simply by cutting off the fuelsupply. In this case, the air compressed in the Compressor will thenexpand in the Expander. This will not only occur with minimal loss inenergy, as working media (air, in this case) acts as an air spring, butsome energy recovery is possible, as heat is transferred from theExpander's walls to the air, thereby cooling the engine internally,while increasing the temperature and, therefore, pressure of theexpanding gases thereby recuperating some of these cooling losses. Thisis in contrast with conventional engines, which require external cooling(either air or coolant), where the losses are irrecoverable.

To implement such a mode of operation, the engine is equipped withelectronically controlled valves and a check valve, which preventspressure drop below the ambient during the “off” cycles. A flywheel isemployed to smooth torque fluctuations or, alternatively, multi-cylinderconfiguration is used instead of or in addition to flywheel.

If the engine is equipped with an external tank and clutches, thecompressor could be disconnected for duration of increased power demand,thus allowing about 50% power boost, since the engine will not spendthis amount of energy for the compression of air. Alternatively, if usedin a car, the braking energy could be partially recovered bydisconnecting the expander and applying car momentum to turn the wheels,which in turn will drive the compressor, which in turn will compress theair and push it into an external air tank.

The embodiments described hereafter are embodiments which may be used toimplement the cycles provided as a part of the present invention.Throughout this document, the references will be made to automobileengine. It should be understood, that the engines provided should beequally applicable for any other applications as well.

One embodiment of the present invention is provided as a rotor andstraight gate embodiment. The rotor & two straight gates embodiment hasa cavity, formed by housing (which includes cover(s)), rotor andgate(s), which undergoes cyclical transformation according togeneralized description above. This engine is shown in FIGS. 3 through7.

FIG. 3 gives both general and exploded views of the engine, whose gates,in this case, are controlled via external cams. It also provides thenomenclature for the main components of the engine, namely a housing andcover plate with an intake and exhaust ports, all of which may be calleda housing in some embodiments, a rotor, two gates, including a c-gate orcompressor gate and an e-gate or an expander gate and an optional s-gateor separator gate.

A rotor, in a course of its clock-wise rotation, together with ahousing, cover and gates forms variable volume cavities, which we willcall now chambers, as shown in FIG. 4 and include a compression chamber(CmP), a intake Chamber (InC), a combustion chamber (CbC), an expansionChamber (EpC), and an exhaust chamber (EhC). Note that not all of thechambers will exists at the same time, as is evident from FIGS. 4 and 5.All chambers except the CbC have variable volumes.

To facilitate the foregoing discussion and referencing FIG. 2 for cycledescription and FIGS. 5 and 6 for corresponding operational sequence, wedefine the following terms: V₁ is the CmC intake air volume (See point 1on PV-diagram, FIG. 1), a maximum volume that this chamber can assumeduring the intake stroke; V₂—CbC compressed air volume (See point 2 onPV-diagram FIG. 1; V₁≈12× to 25× V₂; this is a constant volume CbC.); V₃is V₂ less the volume at the end of combustion (See point 3 onPV-diagram, FIG. 1); V₄ is the EpC exhaust volume of combusted gasses atpoint 4, which corresponds to P₄=1 bar. (See point 4 on PV-diagram, FIG.1)

Operational sequence of the Engine is shown in FIGS. 5 a) through c) anddescribed in the table below.

FIG. 6 Intake Compression Combustion Expansion Exhaust a) Begins InProgress b) In Progress Begins c) In Progress In Progress

Gates in an embodiment of the present invention are driven andcontrolled by one of the following means: external cam(s) with springsas shown in FIGS. 3-6 (this is very similar to poppet valve actuation inmodern engines), and desmodromic cams, when two cams control theposition of the gate (again this is similar to poppet valve actuation inmodern engines, which employ desmodromic cams). Sometimes, thedesmodromic cams are known under the name “conjugate cams”.

Gates also may also be driven by the Rotor itself, which in this caseacts as a cam as shown in FIG. 6. The opposing motion could be providedeither by external cam, or by the return spring, both conventional orair spring. The strategically located tabs on the gate allow gasses toescape under the gate, when such a gate is not participating in acorresponding stroke. For example, the compressed gas would go under thee-gate, which is not part of a compression cycle and is there just “fora ride”. Similarly, during the expansion stroke, the expanding gassesescape under c-gate, which does not participates in the expansionstroke.

Direct electro-mechanical, pneumatic, hydraulic or any other suitabledrives (not shown) are also possible. Besides trivial modifications, forthose proficient in the art, which involve changes in gate geometry,pivoting points, wall's geometry and angles (for example a conical Rotorand corresponding housing walls and gates, etc.), there are numerousmodifications that may enhance the design and operation of the engine,especially as far as sealability of the engine is concerned.

Some of these variations include various configurations of gates such asoval gates shown in FIG. 3, which may offer enhanced sealability, asconventional high-temperature polymer o-rings could be used on ovalshapes. A rectangular, triangular, curved segment, etc. cross sectionsmay be used as well. Gates may also be guided by the housing and/orrollers (see FIGS. 6 and 7). Also, various features on the gate may beuseful: i.e. a lip on the gate is used to enhance the sealing (due to WMpressure acting on this lip) as well as the stop to limit the retractionof the gate as shown in FIG. 38.

Gates may also be guided by the rollers. The gates may be controlled bya stepper motor, a linear motor, an electromagnetic system, a pneumaticsystem, a hydraulic system or any other suitable means for control. Thisallows greater flexibility in operating cycles as well and it may alsoprovide a low constant frictional force and tight sealing between thegates and the rotor.

Combustion chamber may be sectioned in an axial direction. Two, three ormore sections may provide separate FI and thus provide additionalcontrol for part-load operation. For example, if CbC is portioned into 3chambers and fuel is added only to 2 out of 3 sub-chambers—the powergenerated will be ⅔ of full power. Additional important benefit of thisis a potential reduction of NOx formation since relatively cold air willbe combined with hot combusted gasses.

A position of intake port may be variable with respect to Rotorlocation. This will effectively allow varying V₁ and, therefore, thecompression ratio. Alternatively, variable sized CbC (for example byusing retractable plunger) may be used as this would enable variablecompression ratios, without changing the intake volume V₁. Both of theseoptions may be used when greater flexibility in intake volume V₁ andcompression ratio is required.

Nitrogen/Oxygen membrane or Oxygen concentrators may be installed at theintake port of the engine, limiting the amount of N₂ from the air and,therefore the amount of NO_(x) formation. See also U.S. Pat. No.6,640,794,(http://www.csiro.au/hannover/2001/catalog/projects/ceramic.html,http://www.csiro.au/solutions/psw3.html)

For instances where gates are spring-loaded and motion is controlled bythe gas pressure, it is important to assure a small but constant forceexcreted from the blade on the Rotor (or vice versa). To enable this itis possible to have a cam operated spring, such that the force excretedby the spring—F=k x, where k is a spring const and x is deflection, isprovided with more or less constant deflection. I.e. one end of thespring should be fixed on the movable gate, while other end should besupported either directly by cam or by surface that is supported by cam.The cam would ensure that the deflection x remains approximatelyconstant.

The gate, rotor (and Vane, as appropriate) may be split in the middle(perpendicular to axes) and C-Seal/Spring or gas-filled seal/springcould be placed between two halves, which would force the flat faces ofthe gates/rotors/vanes to serve as face seals. An alternative tosplitting gates/rotors/vanes is to split the outer surfaces of theseelements that would serve as a seal themselves. This is shown in FIG. 45for the rotor and FIG. 43 for the gate. The same concept could beapplied to vanes. The edges may be hardened, while the remaining flatsurface could be slightly recessed to prevent interaction with flatsurfaces of the housing, which might break the seal. The recessed volumemay also carry some oil/grease to aid in sealing and lubrication.

The holes in the Rotor are to lighten the Rotor and to allow the gas toescape from under the recess to prevent “floating”.

Both gates are driven by the rotor/cam and back-pressured by the airspring located above the gates. In fully extracted position (FIG. 6)there is little pressure from the air-spring onto the gates. In fullyinserted position the pressure on the gates is high. The oil in the airsprings cavities seals the air spring and lubricates the gates. Oil isalso supplied to the gate's rollers to reduce friction and to form thehydrodynamic bearing. The tails on the gates are to enable support thegates by the rotor/cam and to allow the gasses to get into or from theCbC. Recesses in the housing allow tails in the gates to be fullyinserted, which minimizes the air losses. During the operation, one gateis supported by the roller, while the other is supported by the tail(except for combustion stroke, when both gates are supported by therollers.) The roller serves as a seal.

If integrated Rotor (FIG. 43) is used—the rotor may utilize hydrodynamicbearings, which will double in function as additional seals, thuseliminating the need of bearing supporting the rotor.

Another variation is possible comprising gates that are straight or arepivoting inside the rotating rotor. The basic geometry of the engine isshown in FIGS. 6 and 8. The differences with the straight gate designare minor. The gates pivot in an arc rather than slide. Operation ofthis engine is analogues to that of the straight gate design and isshown in FIG. 9. In addition to variations described for straight gatedesign, the variations to Pivoting Gate geometry might include: gatesthat are be pivoted by flexural pivot bearings, gates that are pivotedon the same pivot axes.

Another embodiment of the present invention includes a rotor with twopivoting gates. This embodiment may incorporate a scavenging design.Scavenging may be accomplished in number of different ways, includingthe use of scavenging gate designs. Other ways may include universalmethods, like the “air knife” concept that is applicable to mostembodiments.

The rotor with two pivoting gates embodiments implementing a scavengingdesign has a cavity, formed by a housing, a cover, a rotor and pivotinggates, which undergo cyclical transformation according to the aforeprovided descriptions. This engine is shown in FIG. 10. Gates arepivoted into operating position by external cams (not shown, but similarto those shown in FIG. 12). The cover is removed reviling and identifiesthe main components of the engine which include: a housing (a coverplate, not shown), a rotor, two pivoting gates, which simultaneouslyserve as walls of the engine, a c-gate or compressor gate an e-gate orexpander gate. Two gates do not have to be the same shape.

The rotor, in a course of its rotation, together with a housing, a coverand gates forms variable volume chambers, as shown in FIG. 9. Thechambers formed include a compression chamber (CmP), a combustionchamber (CbC), and an expansion chamber (EpC). Note that not all of thechambers will exists at the same time, as is evident from FIG. 9. Allchambers except the CbC have variable volumes.

Unlike previous Pivoted embodiment, there are no Intake and Exhaustchambers and ports (though it is possible to have them, if beneficial)and engine operates in “2-cycle” scavenged mode. In this case, evenscavenging fan blowing the fresh air charge is not necessary sincescavenging chamber is a wide open space.

Operation of this engine is analogous to straight gates and PivotedGates embodiments. Variations of the invention are shown in FIG. 10where the gates are pivoted around pivot points. An alternativearrangement has the side gates in a sliding configuration. Appropriatelymounted bearing guides should be able to accept the side loads from highpressure WM. Finally, a combination of slide and pivot could be employedas well.

Altogether different variation of scavenging designs involve locatingthe intake and Exhaust ports in close proximity to each other,preferably in opposition to each other and blowing the air through theintake port, thus creating an “Air Knife”, which will act as a “wall”preventing a cross flow from the exhaust chamber into an intake chamber.The Air Knife will “drag” the exhaust gasses out of exhaust chamber.This concept is shown in FIG. 11 and is applicable to most of theembodiments that are discussed in this application.

A rotor and pivoting connected gates embodiment is also provided inaccordance with an embodiment of the present invention. This embodimentis similar to pivoting gates design, except that the gates have the samepivot point and are connected to each other, thus forming what appearsto be one gate with two ends that serve as e-gate and a c-gate.Geometrically this represents a segment of a hollow cylinder.

The CbC is located inside of the hollow cylinder. This limits the accessto it from the top, but since it is possible to access it from bothsides, this should not represent the major problem. The access is neededfor fuel delivery and pressure/temperature measurements inside of theCbC.

Operation of this engine is analogous to straight gates and pivotedgates embodiments. The gate is driven in oscillatory manner around thecombustion chamber by a spring loaded 4-bar link mechanism, as shown inFIG. 12, or by symmetric 4-bar mechanism, which, in essence becomes adesmodromic drive, or by any other suitable means.

There may be a number of variations of this very compact design. If weallow the covers to be rigidly attached to the Rotor and thus turntogether with the Rotor, as will be described in FIG. 41, we can formgroves within these covers which will serve as cams to drive the gate.This variation is especially great for HCHC, since no access to CbC forfuel injectors is required. For HEHC operation, the fuel injector couldbe located on the side of the engine—perpendicular to Gate's pivot axis.

Pivoted gates may be transformed into a completely rotary gate, albeitturning with a non-uniform speed. The motion can be continuous orintermittent with short dwells during which CV CbC is formed. Finally,the gate itself may serve as a CbC.

Another embodiment of the present invention provides an engine with tworotors and two gates. The two rotors and two gates embodiment is shownin FIG. 13. It consists of two rotors, a c-rotor and an e-rotor; and twogates, a c-gate and an e-gate, and the housing. Transfer channels,containing the CbC connect the cavities formed by housing, rotors andgates. Rotors are coupled mechanically via gears, chains or timingbelts. Covers, shafts, injectors, etc. are not shown for clarity. Forthe sake of further discussion, we will call this embodiment a “singledeck”, which, basically, corresponds to a single-cylinder engine.

Rotors are basically D-shaped; having a rather large constant radiussegment is essential for valving function of the rotor, which will bedescribed below. D-shape is here used to indicate a mostly circulargeometry with the straight cut segment removed from the circle. Cornersare rounded, of course for smoothness of operation. Such a rotor isreferred to herein as a D-shaped or single-lobe rotor. The rotor, in acourse of its clock-wise rotation, together with housing, covers andgates forms variable volume cavities or chambers, shown in FIG. 13including a compression chamber (CmP), an intake and transfer chamber(InC), a combustion chamber (CbC), an expansion chamber (EpC), and anexhaust chamber (EhC). Note that not all of the chambers will exists atthe same time, as is evident from FIG. 5.

During operation of this engine air enters the intake port into a CmCformed c-rotor, gate and the housing. Air is transferred then in acourse of a large part of its angular travel, without changing itsvolume.

During the transfer part of the operation, air is trapped within theCmC. This could be used to our advantage to increase the efficiency ofengine operation by transferring the heat from the expander's walls tocompressor's walls via heat pipe, by locating the second “deck” inopposition to the first, i.e. by having the e-rotor of the second “deck”being coaxial with c-rotor of the first “deck”.

After transfer phase, the c-gate engages the c-rotor and air is beingcompressed into a constant volume CbC by the leading edge of the “D”,while simultaneously it is being inducted on the trailing edge of the“D”. After all air is compressed into CbC, the radial part of theD-shaped Rotor plugs the hole leading to a CbC. Thus, the rotor executesthe additional function of a valve.

At this moment of time, the e-rotor, which rotates in the same oropposite direction, depending upon design, still plugs the hole leadingfrom the CbC into the expansion chamber. The overlap of these two rotorsdefines the length of constant volume time.

Variations of the above embodiment may include having two independentrotors. Such an embodiment affords great flexibility to design as therotor shape may deviate from the D-shape. While having a rather largeconstant radius segment is essential for valving functions of the rotor,the remaining non-constant radius part may assume any shape, fromstraight to concave.

There could be more than one “cut” in the Rotor shape—two or three, oreven more are practical. Correspondingly, such a rotor would be called2-lobes, 3-lobes, etc. This would increase the power density of theengine.

Gates could be straight or curved, sliding inside of the Housing orpivoted. Rollers could be used for guiding purposes and to reduce thefriction.

If rotors are of “integrated type”, i.e. they are coupled to covers thatrotate together with the rotor as shown in FIG. 43, the gates may bedriven by cams located on the end plates themselves.

Rotors may be of different diameters or thickness to accommodate forV₄>V₁ condition of the HEHC. The gates may be driven by the rotors (ifspring loaded; spring might be an air-spring) or by external cams orelectromagnetic, hydraulic or other means.

The rotors do not have to rotate with the same speed (and direction).Having rather long dwells, during which WM is being transferred from oneposition to another, may be reduced or even completely eliminated, byhaving multi-lobed rotors and/or rotating two rotors with differentspeed.

The 2-rotor/2-gate embodiment may be considered a building block forlarger systems. While this is true for any of the embodiments describedabove, this is especially beneficial for this engine. FIG. 14demonstrates the example of 6-rotor/12 gate embodiment, which benefitsin that it doubles the output of the equivalent 2-rotor/2-gate system aseach pair of rotors fires twice in a course of a single revolution. Toclarify, if a 2-rotor/2-gate rotor power output is P, then a 6-rotors/12gates system will produce P×3×2=6×P.

Especially compact configurations may be made with a single centrallylocated c-rotor and two, three or more e-rotors, having the same ordifferent sizes, same or different numbers of lobes, same or differentrotational speed, etc. E-rotors may be located symmetrically around thec-rotor; thus, forming a generally triangular configuration in the caseof three e-rotors or a quad configuration in the case of four, etc.

In another embodiment of the present invention a two rotor engine withmultiple gates is provided. Multiple variations of basic engine arepossible and may be apparent to those skilled in the art. Oneparticularly interesting example is that of axial vane engine in whichthe vanes move in axial direction instead off a radial direction.Appropriately locating air intake slots and exhaust slots in the housingand/or cover plates allows implementing the HEHC, M-HCCI, M-HCCI+FI,HEHC-S, etc.

In another embodiment of the present invention a single rotor, multiplevane engine configuration is provided. In this geometry, a rotor rotateswithin the housing and carries with it two (or more) sets of vanes, eachset consisting of c-vane, which compresses a fresh air charge into aCbC, and e-vane, which expands the combustion products whiletransferring power through the rotor to the shaft. The engine, shown in

FIGS. 17 through 19, undergoes cyclical transformation according togeneralized description above.

FIG. 17 gives both general and exploded views of the engine and alsodefines the nomenclature for the main components of the engine, whichinclude a rotating rotor, attached to an output shaft, and two (or more)sets of vanes, including a c-vane or compressor vane, which glides in aclose proximity to a c-cam formed by an insert, without touching it. Theposition of the c-vane is controlled by the pin, guided by the firstgroove cam in housing base (FIG. 20 c). A small gap between the vane andthe c-cam surface of a movable insert, which exists to accommodatemanufacturing tolerances and thermal expansion, is closed by a set ofapex and face seals located on the c-vane and piston-like seals locatedon the rotor.

An e-vane or expander vane glides in a close proximity to an e-camformed by a housing base, without touching it. The position of thee-vane is controlled by the pin, guided by the second groove cam inhousing base (FIG. 20 c). A small gap between the e-vane and the e-camsurface of a housing base, which exists to accommodate manufacturingtolerances and thermal expansion, is closed by a set of apex and faceseals located on the e-vane and piston-like seals located on the rotor.

The housing base (with an exhaust port), the housing cover and a movableinsert (with an intake port), may be referred to herein with regards tosome embodiments as the “housing.” The housing (base and cover) inaddition to defining (enclosing) the cavities, has a curved wall,forming an e-cam, which guides the apex seal of e-vanes. The flatsurface on either the housing base or the housing cover, or both, hastwo grooved cams, which control general position of the vanes.

The movable insert, in addition to defining (enclosing) the cavities,has a curved wall, forming a c-cam, which guides the apex seals ofc-vanes. The insert is rotatably mounted within the housing base. Itcould be rotated ±30 degrees, (or more, if necessary) while stationaryor dynamically, to change the angle and, therefore, the phasing betweentwo cams. This angle will control the length of time the constant volumecombustion chamber is formed. The phaser for changing the angledynamically, (i.e. while the engine is running), is not shown.

Working cavities (chambers) are formed by the housing, rotor, vanes andsealing components of the engine. These are demonstrated in FIG. 18.

The chambers are formed by the variable volume cavities existing betweenthe housing, rotor, vanes, and sealing components. These chambers, as wewill call them from now on, are undergoing transformation, wherein thevolumes are swept from a minimum volume, V₂, to a maximum volume, V₄.The combustion chamber has a constant volume V₂. The expansion chamber,increases its volume from V₂ to V₄. The exhaust chamber decreases itsvolume from V₄ to 0. The intake chamber increases its volume from 0 toV₁.

The engine works by executing one of the cycles defined above. In acourse of its operation, many strokes happen simultaneously. As shown inFIG. 19 the engine begins at the intake portion of the cycle. Duringintake a fresh volume of working medium is admitted through the intakeport located either on the side of the insert or within the center of it(the later arrangement is shown in FIG. 19.), during a substantial partof the shaft rotation, such rotation being approximately 45 degrees forthe 2-set configuration shown in FIGS. 17-19.

As the rotor rotates (clockwise), it pushes and pivots the c-vane withcorresponding seals along the c-cam surface of the insert. The WM iscompressed into a CbC. The “exit port” of the CbC is closed by thehousing.

Compression is shown in FIGS. 19 a and 19 d. Intake is shown in FIGS. 19a, b, and d. The end of the compression stroke and the beginning ofcombustion stroke is shown in FIG. 19 b. The combustion process proceedsto its completion, while the volume of CbC remains constant. Theduration of time during which it remains constant is controlled by thephasing between the c- and e-cams, and, therefore by position of themovable insert.

The end of combustion and the beginning of expansion is shown in FIG. 19c). Burnt WM exits the CbC and pushes the e-vane with a very largepressure but over the small area exposed to this burnt WM. As rotationcontinues, area is increased, while pressure is decreased, causingrelatively constant torque over the substantial part of the expansionstroke.

The leading edge of the e-vane, meanwhile, pushes the exhaust fromprevious cycle out of the exhaust port. Both expansion and exhaust areshown in FIGS. 19 a), and d)

Besides trivial modifications, for those proficient in the art, whichinvolve changes in rotor or vane geometry, pivoting points, housinggeometry and angles (for example a conical Rotor and correspondingHousing walls and Vanes, etc.), there are numerous modifications thatmay enhance the design and operation of the engine, especially as far assealability of the engine is concerned. Some of these modificationsinclude an embodiment shown in FIGS. 17 and 19, where both vanes (ineach set) run continuously on two different cams, including both a c-camand an e-cam. It is possible and may be beneficial to run both vanesintermittently on the same cam, located on the housing. The CbC will belocated within the rotor as with earlier embodiments, but the CvC willbe defined by the profile of the cam rather than by the mutual phasingof the cam action on vanes. This is shown in FIG. 20 b).

Straight vanes moving in a linear way may be used in place of pivotingvanes both in the basic design configuration (shown in FIGS. 17 and 19)as well as in all variations shown in FIG. 20 b). These can be supportedby rollers, as required for enhancing load bearing capacity andsealability.

A phaser may be used to continuously vary the dwell (duration ofconstant volume CbC)

Apex seals may be of a conventional type, like those used in a Wankelengines, or of any types discussed in this application. FIG. 17, forexample, shows a circumferential seal.

Vanes may be single or multi-body design.

Half ring seals have to be energized in both circular dimension and in aflat dimension, either by its own geometry or by separate springs.

A sealing grid is formed by a plurality of half-ring, apex and faceseals located within the vanes, the rotor and the housing.

As with most embodiments disclosed in this application, it is possibleto implement the HCHC by injecting a lean fuel/air mixture during theintake stroke or shortly thereafter. The WM should reach its “criticalconditions”, described in the homogeneous charge hybrid cycle (HCHC) anytime during the constant CbC volume phase. To assist in reaching thiscondition, one can coat the section of the housing walls (e-cam) with asuitable catalyst, which will initiate the combustion within some smalldelay (a fraction of a m-sec.) after the WM is exposed to such acatalyst as shown in FIG. 20 c.

Another embodiment of the present invention includes a single pistondesign with 2 cylinders. This embodiment, sometimes referred to as adouble-acting piston engine, may be modified to work on high efficiencyhybrid cycle and may be operated in digital mode as shown in FIG. 22.

FIG. 22 shows the 3D view of double-acting piston engine of specificallycompact configuration. The cam, which drives the cylinder (analternative configuration where piston is cam driven is also possible),may be of any suitable type: face, groove, barrel, plate, etc. It ispreferable that such a cam has a dwell, which imparts no motion to thecylinder during the combustion process, and would provide a smallerintake volume than expansion volume. This type of motion together withappropriate timing of valves implements the HEHC for piston-likeengines. It is also possible that the profile of the cam provides a veryrapid expansion of combusted gasses in the temperature range where NOxis formed, typically from 1350 to 1100 deg C. This limits the time theN2 and O2 have to recombine to form NOx, thus potentially, lowering theNOx emissions. The cam, may also serve as a flywheel.

FIG. 22 displays the spherical combustion chamber, which lowers the heatlosses during the combustion process and retains a constant volume dueto momentarily stops imparted by the cam motion.

The valves, fuel pump (not shown) and oil pump (not shown) are alldriven by the internal cams, one of which is shown in FIG. 22, and/orgears. The intake and exhaust manifolds (not shown) are located withinthe central post.

A gang of two engines, not shown, may simply be connected by a hexdrive. More than two engines may be connected to obtain the requiredpower. The benefits of the multiple-engines configuration are thatphases may be shifted in increments of 60 degrees to supply more uniformmotion to the load as well as finer control at the part load operations.

If the cylinder is made out of a soft iron or, a high-temperature supermagnetic materials and is surrounded by electromagnetic coil, then powergenerated by the engine can be converted directly into electricity. Inaddition, if electromagnetic force is used to compress the air as well,one can implement this engine without the drive cam. All of the valvesand pumps may also be electromagnetically driven or cam driven. Tosupply the mechanical energy for compression, the electric energy can bestored in suitable batteries and/or supercapacitors. An efficientcontroller would be required as a substitute for a camed-controlledmotion. Finally, if cylinders and pistons are arranged as segments ofthe torus, (FIG. 25), and pistons are made of the soft magnetic materialor, or better yet, high-temperature super magnetic materials, then therewill be no need for the valves, which are replaced by appropriate ports.The cylinder walls may also be made of compounds, (i.e. partially madeof strong metal) where compression and, especially, combustion andexpansion take place, and partially made of non-magnetic material, wherepiston acceleration/deceleration takes place. Energy is expanded foracceleration of pistons and extracted for deceleration of pistons, whichresults in a conversion of chemical energy of fuel into electricalenergy generation. It is clear that similar results could be obtainedwith cylindrical configurations, rather than toroidal. This has thepotential to simplify the mechanical components of the engine.

There may also be multiple configurations of rotary type of engines,HEHC combined with digital operation modes. Some of these configurationsare shown in the following figures.

Various configurations described herein, especially rotary-types,require sufficient sealing to enable efficient operation of the engine.These sealing solutions are described below.

A wedge seal is show in FIG. 40 b. A flat metal or composite materialwith a angled profile on one or both sides such that any tangentialmotion due to the rotation of the rotor is translated into axial forceto increase the sealing pressure.

An integrated rotor is shown in FIG. 43. In this sealing system therotor face seals are eliminated by incorporating the rotor with thecover and allowing the cover to spin with the rotor. The sealinglocation now moves from the face of the rotor to the radial surface ofthe cover.

Another embodiment of the invention includes the use of liquid metalseals. This concept uses low melting temperature metal captured in agrove on the face of the rotor. When the rotor spins, friction and gastemperature melt the metal which then acts as a liquid seal.

Oil barrier seals may also be used with embodiments of the invention.Oil is supplied to the face of the rotor in such a way that it collectsin a grove along the face and act as a barrier preventing the workinggas from escaping. A similar concept is the use of oil saturated“cloth”, but the cloth aids in containing the sealing oil and reducingoil leakage.

A split rotor seal is another embodiment of the present invention. Theseal includes 2 parts with a Wankel-style seal between the parts or a0.01×″×0.01″ rectangular wire as a seal. Each half of the rotor seal isenergized by a spring and allowed to float inside to housing to minimizethe working gap.

A split rotor may be provided where there are multiple “slices,” ˜0.1″thick, separated by oil film. The rotor is split into multiple layersseparated by a fluid film similar to a wet clutch mechanism. As therotor spins the fluid layer increases thickness separating the rotorplates and closing the face to cover gap and forming a seal.

Nanocarpet (nano-wires, nano-brushes) may be provided that are saturatedby oil. Nano sized fibers are grown on the face of the rotor andposition to contain an oil layer, which acts as a barrier sealpreventing the working gas from escaping.

Another embodiment of the present invention includes a single pistonengine with an electromagnetic coil. The geometry of this engine issimilar to the embodiment previously described as a single piston,2-cylinder engine. In this embodiment if the cylinder is made out ofsoft iron or, better yet, high-temperature super magnetic materials andsurrounded by electromagnetic coil, then a cam may be substituted withan electromagnetic drive.

The power generated by the engine is converted directly into electricitythrough the following steps: (1) electric energy, stored initially in asmall battery, charges bank of supercapacitors; (2) a controller thenenergizes the coil and moves piston to induce and then compress the air;(3) fuel is added as usual and combustion occurs, leading to anexpansion stroke;(4) the controller de-energizes coils and switches themto recharge the supercapacitors; and (5) excess electricity is used todrive the electrical load. All the valves/pumps are cam orelectromagnetically driven.

The cycle is most suitable for HCHC operation, so that a dwell is notrequired.

Another embodiment of the present invention includes the use of multiplepistons with electromagnetic coils.

If cylinders and pistons are arranged as segments of the torus, (FIG.25), and pistons are made of the soft magnetic material or, better yet,high-temperature super magnetic materials, as in the embodiment above,then there will be no need in valves, which are replaced by appropriateports. The cylinder walls may be made compound, (i.e. partially ofstrong metal) where compression and, especially, combustion andexpansion takes place, and partially made of non-magnetic material,where piston acceleration/deceleration takes place. The energy isexpanded for acceleration of pistons and extracted for decelerationallowing for the conversion of chemical energy of fuel into electricalenergy generation. It is clear that similar results may be obtained withcylindrical configuration, rather than toroidal. This has a potential ofmechanical simplification of components of the engine.

Operation of the engine is similar to the one described as a singlepiston with an electromagnetic coil embodiment.

Another embodiment of the present invention uses a rotor with multiplepistons. FIG. 25 shows a variation of McEwan Ross “Rota” engine. In thisconfiguration, fresh air charge is pushed by a small turbofan (whichalso serves as a flywheel and driver for pistons), it works as aturbocharger/scavenger or as air knife/scavenger. By scavenger we meanthat in the same operation the exhaust products are being pushed our asthe fresh charged is pulled in. This corresponds to 2-stroke version ofHEHC. The fresh air charge is then compressed by the pistons, whichexecute a complex rotational/oscillation motion driven by the camfollowers riding within the slots located on the inside surface ofturbofan/flywheel/driver. A straight version of slots is shown forsimplicity. However if curved slots are used, the compression cycle isconcluded with a short pause, during which two adjoining pistonspractically do not move with respect to each other. During this pause,the space between these adjoining pistons remains constant. Thiscorresponds to constant volume combustion (CvC). The fuel should beinjected at some prior instance so it has time to mix with the air. Thisis accomplished by means of high pressure fuel injector ported to theFrame and corresponding ECU (Electronic Control Unit) and data from theposition and various other encoders. This fuel injection mechanism isstandard on modern diesels and applicable to all configurationsdiscussed in this applications and will not be repeated for the sake ofbrevity.

A 4-stroke version of this configuration may be provided, where intakeand exhaust ports are separated, but requires a more complicated drivingmeans, which could include cam or double eccentric (not shown). Inaddition, as shown in FIG. 25, the driver with the slots may be madestationary or oscillatory, while pistons may be driven by the eccentricdual-eccentric drive with corresponding camming or non-cylindrical gearsto provide for a CvC chamber. In this case a stationary constant volumecombustion chamber is created and conventional poppet valves may beused.

A rotor driver, which also serves as an air-knife scavenger and aflywheel is also provided, which has slots that engage rollers onpistons. The rotor is driven eccentrically with respect to motion of thepistons.

Another embodiment of the present invention has dual pistons and a dualeccentric drive. In this embodiment two pistons are operated on bothends, hence the name dual pistons. The firs piston is a square pistonwith a round hole in the middle to accept an eccentric drive. The secondpiston has rectangular recess in which first piston slides. The engineis driven by dual eccentric drive, which may be implemented in one oftwo ways. The square piston (not shown) may driven by a dual eccentricdrive, such as those shown for different embodiments in FIG. 26. Thesecond piston with a rectangular recess is not driven but can slide in aperpendicular to the square piston direction. The dual eccentric driveis mechanically equivalent to a 2-link system and as such could bedriven to create a short dwell during which a constant volume CbC isformed. Ports are located in the stationary housing to allow inductionand exhaust.

FIG. 27 illustrates another variation of the dual drive engine in which:the square piston is driven by an eccentric, while, the second pistonwith a rectangular recess (“Rectangular Piston”) is driven by anothereccentric.

In the embodiment, shown in FIG. 27, square piston is driven by aneccentric, while “rectangular piston” is driven by another eccentric.The net effect of this arrangement is that the second “rectangularpiston” rotates around the main shaft. The housing houses the intake andexhaust ports and fuel injectors (not shown). During the mutual motionof pistons, the air enters the second piston through the intake port,compressed. The fuel is injected and combusted at substantially constantvolume and combustion products are expanded to a larger volume thanintake and then exhausted through exhaust ports. Dual eccentrics, which,by the way may be used in many other embodiments as well, may allow adwell, which corresponds to an isochoric heat addition process (constantvolume combustion).

Another embodiment of the present invention includes a two opposedpiston configuration. Internal combustion engines are used to powervehicles and other machinery. A typical reciprocating internalcombustion engine includes a body, a piston, at least one port or valve,a crankshaft (which serves as a drive shaft), and a connecting rod. Thebody defines a cylinder. The piston is located inside the cylinder sothat a surface of the piston and a wall of the cylinder define aninternal volume. The port is located in the body, and allows air andfuel into and exhaust gas out of the internal volume. The valve ismovable between a first position wherein the port is open, and a secondposition wherein the valve closes the port. A connecting rod isconnected between the piston and the offset throw section of thecrankshaft, such that reciprocating movement of the piston causesrotation of the offset throw section of the crankshaft about acrankshaft axis.

A reciprocating engine of the above kind typically has a cylinder headthat defines the internal volume together with the surface of the pistonand the wall of the cylinder. Heat is transferred to the cylinder headand conducts through the cylinder head, thereby resulting in energylosses from the internal volume and a reduction in efficiency. One wayof increasing efficiency is by reducing an area of the surface of thepiston and increasing a stroke (a diameter of a circle that the offsetthrow section follows) of the piston. Ignition delay prevents thecombustion from completing before the movement of the piston lowers thepressure and temperature required for autoignition, so that the enginecan only be run at lower revolutions per minute with a correspondingreduction in power. Since a conventional piston engine is symmetric(intake stroke is the same as the exhaust stroke), the expansion strokeis limited to the intake compression stroke resulting in a relativelyhigh temperature of the gas when it is exhausted. The heat in theexhaust gas is an energy loss that results in a reduction in efficiency.Higher efficiency may be gained by expanding the exhaust gas until allof the usable temperature and pressure is extracted. Conventionalengines have a fixed geometry resulting in a given compression ratio forall operating conditions. Higher efficiencies are achievable with highercompression ratios; however, different engine operating conditionsrequire different compression ratios for highest efficiency. Due to thefixed geometry of a conventional engine only one compression ratio isachievable resulting in a compromised efficiency at other operatingconditions.

The invention provides an internal combustion engine, including a bodydefining first and second cylinders in communication with one another(not necessarily in line), first and second pistons in the first andsecond cylinders respectively, surfaces of the pistons and walls of thecylinders defining an internal volume, at least one port in the body toallow air and fuel into and exhaust gas out of the internal volume,first and second drive shafts, each having a bearing section mounted forrotation on a respective drive shaft axis through the body and eachhaving an offset throw section, the first piston and offset throwsection of the first drive shaft being connected and the second pistonand the offset throw section of the second drive shaft being connected,such that reciprocating movement of the first and second pistonsincreases and decreases a size of the internal volume between minimumand maximum sizes and causes rotation of the offset throw sections ofthe first and second drive shafts about the drive shaft axes, theminimum size of the internal volume being nearly constant volume andadjustable between a large size for lower compression ratios and a smallsize for higher compression ratios, and one port for intake and one portfor exhaust mounted to the body opened and closed by the movement of thepiston allowing for asymmetric expansion to compression ratios. Themovement of the piston and opening and closing of the port allows andrestrict flow respectively of at least the air into the internal volumefor one cycle of the pistons.

The internal combustion engine can adjust the compression ratio, intakeport open time and duration, exhaust port open time and duration, andexpansion ratio by means of phasing one drive shaft to another though arotary device mounted on the driveshaft. The process implemented by theabove device can also be created by using two rotors mounted on twoshafts instead of two pistons and two cranks This rotary device canrotate one shaft relative to another while the engine is in operation orstationary

Another embodiment of the present invention provides an internalcombustion engine, including a housing defining a larger and smallerrotor in communication with one another (not necessarily end-to-end).The larger and smaller rotors in the larger and smaller end of thehousing, respectively, surfaces of the rotors and walls of the housingdefining an internal volume, at least one port in the housing to allowair and fuel into and exhaust gas out of the internal volume, first andsecond drive shafts (or, if inline, possibly one cam shaft), each havinga bearing section mounted for rotation on a respective drive shaft axisthrough the housing. The larger rotor draws in fresh air and compressesit. A portion of the compressed air is pushed through a port or valveand injected into the exhaust gas side of the rotor. This air injectioncreates a reaction in the exhaust to help reduce hydrocarbon emissionswhile also reducing the intake air volume. The remaining compressed airis then transferred to the smaller rotor through a valve or port wherethe air is compressed more. This allows the second rotor to multiply thecompression ratio (the amount of multiplication is dependent on thevolume ratio between the two rotors; for example if the larger rotor istwice as large as the smaller rotor, it will double the compressionratio. If the larger rotor is three times the volume of the smallerrotor, it will triple the compression ratio, etc.) Combustion occurs attop dead center on the smaller rotor where volume is nearly constant forthree rotor angle degrees (nine crank angle degrees). After combustion,the exhaust in the smaller rotor's housing exerts a force on the rotorthus rotating the shaft. The expansion stroke on the small rotor equalsthe compression stroke on the small rotor. This pressurized exhaust gasis then transferred back to the larger rotor through a valve or portwhere the air is expanded more. This allows the second rotor to multiplythe expansion ratio as stated above for the compression strokes. At thispoint compressed fresh air is injected through a port or valve into theexhaust gas causing a secondary reaction reducing the unburnedhydrocarbons. This second expansion is greater than the first stagecompression due to the reduction in compressed air on the compressionside. Then, it is able to escape the housing via a port in the largerrotor's housing.

Besides trivial modifications, for those proficient in the art, whichinvolve changes in ports and piston sizes, shape and location thenon-trivial change is to locate two piston in co-axial or nearly coaxialconfigurations (double deck as opposed to a single deck).

Another embodiment of the present invention includes a two rotorembodiment that is based on a gerotor design as shown in FIG. 35, inwhich both inner and outer gerotors may rotate with constant speedaround fixed axes within the Housing. The inner gerotor uses one lesstooth than outer one. The housing has an in-line intake and exhaustports and uses turbofan (not shown) to enable an air knife scavenging.This enables HEHC-S (scavenged) operating cycle.

A low count gerotors is preferred, such as 3-4, as shown in the FIG. 35,as the almost constant volume is created when the inner gerotor lobeengages the corresponding lobe of the outer gerotor. A 2-3 lobe rotormay be used as well, but it creates a very long dwell (a constant volumeduration). Higher order gerotors may be used as well, especially forHCHC operation when duration of the CV CbC is not important.

The inner rotor rotates and drives the outer rotor. A spring-loaded oroil supported rollers aid in sealing and reduce friction. The port hasto be shaped and located in such a way that intake volume is less thanexpansion volume. No CvC exists if the rotors are driven with a constantspeed, but quasi-constant volume is possible due to relatively slow rateof volume expansion that exists right after the combustion.Alternatively, using a drive with a short dwell makes it is possible toimplement a true HEHC. Again, the frame may be driven by cam/gears toimplement the true CvC as well. An inner Roller may be eccentric-driven.A digital mode can be used as in all above configurations as well.During operation of this embodiment, the variable volume cavities, orchambers, are created by inner and outer gerotors and housing covers.Each chamber rotates and in a course of its motion changes the volumefrom minimal, V₂, corresponding to CbC volume, to a maximum, V₄,corresponding to an Exhaust volume. Fuel is injected through stationaryFI (not shown) located within covers. The operation is typicallyaccording to a HEHC-S cycle where air is scavenged (exhausted andinduced), air is compressed, fuel is injected and combusted, and thecombustion products are expanded. While a ¾ configuration is shown ⅔, ⅘,etc. configurations are equally possible. This engine may also beoperated in a digital mode.

Another embodiment of the present invention includes a single vaneconfiguration. This embodiment is based on a gerotor design shown inFIG. 36, which employs a housing (the outer gerotor) and a single vane(an inner gerotor), which rotate around its axis while the axissimultaneously rotates (on the eccentric) with respect to the housing.The inner gerotor uses one less tooth than outer one. As in previousembodiment, a low count gerotors is the preferred embodiment, such as3-4 configuration, shown in the FIG. 36, as the almost constant volumeis created when the inner gerotor lobe engages the corresponding lobe ofthe outer gerotor. However, 2-3 lobe configurations may be used as well,but it creates a very long dwell (a constant volume duration). Higherorder gerotors may also be used, especially for HCHC operation whenduration of the CV CbC is not important.

The housing of this embodiment together with the vane, forms 4 (in thisinstance) variable volume cavities, or chambers, which are analogous toa 4-cylinder piston engine. Vanes engaging each chamber, in turn,simulate a 4-stroke operation. The working medium will be induced,compressed, combusted, expanded, and exhausted.

The housing will house a constant volume CbC, which may be located inhousing proper, or in the cover. A conventional poppet valves orspherical valves or disk valve may be used to control timing of intakeand exhaust stroke. The valves are not shown in this figure. If CbC islocated within housing as shown, the cylindrical valves may be employed.These valves would be concentric with the housing and would rotateexposing the opening from the CbC to Intake or Exhaust ports. Havingintake valves open while chamber volume is being decreased allows asmaller intake volume than exhaust volume, thus achieving the Atkinsonpart of the cycle. This embodiment may also be operated in a digitalmode of operation and may be used with a fuel injection system.

Conventional low-pressure and/or high-pressure fuel injectors may beused. However, these injectors and pumps typically are large (not usablefor small engines) and very expensive.

An alternative approach is to use very compact and economical system,shown in FIG. 37. It consists of the following parts: (a) a cam, whichprovides a constant rate of rise to a piston pump, (b) a fuel manifoldconnecting fuel pump cylinder with an injector or one or more by-passlines leading back to fuel tank, (c) one or more magnets that actuateby-pass piston plugs (d), fuel lines leading to fuel injector and to orfrom a fuel tank, and (e) one or more check valves (not shown) toprevent backflow of fluid into the tank and from the fuel injector.

The piston supplies high pressure fluid (fuel) to fuel injector, whichwill “fire” as long as high pressure is applied to its needle valve (notshown). To generate high pressure both by-pass piston plugs should beblocking the by-pass channels. If one or both plugs are in “open”position—the fluid pressure is not sufficient to open (or “fire”) FI.The fluid is then returned to fuel tank (not shown) via return line. Theby-pass lines are very small diameters holes in the manifold. Verylittle motion is required for the plugs to block the by-passline—therefore simple magnets may be used to provide very fast motion.

The operation of the system is very simple as well. During the initialmoment of time, one plug is closed and the second plug is closed;therefore, the pump does not deliver the fuel in spite of the fact thatpiston is moving as driven by the cam. A signal from controller is sentto currently open plug to be closed. After very short delay the plugexecutes this motion, pressure starts building up and FI “fires”.Simultaneously, or with some delay, the second signal opens up thesecond plug, thus, reliving pressure in the fuel pump cylinder andstopping the injector. Therefore, the FI will be fired only during thedelay between two signals, which may be very short. This will ensurethat fuel may be delivered in required quantities.

For 5-vane engines, the cam has 5 segments, each generating its ownpressure pulse. If two injectors are used—they may be driven from thesame or different cams, which may supply the same or different pressures(which is actually the function of the fuel injector spring, rather thana pump).

One more alternative that is worth mentioning is using a piezo-crystalstack to inject fuel directly at the point of use. This is possible dueto the fact that each injection requires relatively little amount andfuel pressure.

It may be desirable under certain circumstances to allow small amount ofhighly compressed air to be trapped between the rotor, compressor rotorand the housing. This will force this trapped air through very smallnozzles into CbC during the fuel injection. The high speed, highpressure air streams will break the fuel streams, evaporate the dropletsand aid in mixing of fuel and air. Alternatively, it is possible toimplement the entire fuel injection mechanism (using the venture effect,or just a plunger driven by this “leftover” pressurized air)

As it was discusses above, having ability to trigger the engineoperating under a homogenous charge compression ignition trigger (HCCI)cycle may prove to be very beneficial for a practical implementation ofsuch engines. A multitude of triggers may be used in the environment ofrotary engines that have constant volume combustion or near constantvolume combustion. These triggers include a catalyst, a plunger, toimplement a volume change, or a temperature increase caused by a sparkfrom an ignited spark plug.

Having a constant volume combustion chamber (CV CbC) allows a largeoperating time window for autoignition to occur. This is due to the factthat autoignition can occur any time after constant volume combustion iscreated (which is equivalent to TDC point of conventional engines). Evenif autoignition occurs before TDC, due to geometrical constrains, theface of the rotor exposed to combustion pressures is very small, whichconsequently minimizes the effect of premature combustion. Additionally,the geometry of the engine offers a unique opportunity to “trigger” theauto-ignition reaction by means other than spark ignition or fuelinjection. In the proposed engines the issue with the control window maybe resolved on two levels. The timing of ignition event, while importantis not critical; therefore, if auto-ignition occurs slightly before theend of compression stroke (a point that could be compared with TDC), thedifferential force on the moving element (Rotor) of the engine will bevery small, as will be explained later. Any occurrence of auto-ignitionafter the “TDC” is ok as well since it will occur within the CV CbC,i.e. at the time when forces acting upon the moving element (Rotor) willact in radial direction only and will be fully absorbed by the bearingsso that they do not impede or even affect the motion.

It is also a relatively easy to introduce a “trigger” into the system,due to existence of CV CbC, by exposing the CbC to catalytic substance,as it will be explained below. The combustion will occur due tostimulated ignition which may be accomplished by various means describedin patent application PCT/US07/74980, incorporated herein by reference.However, the simplest way to stimulate ignition is to deposit acatalyst, such as nickel, onto one of the surfaces that makes the CV CbCin such a way that when chamber containing the compressed air/fuelmixture in slightly “sub-critical” condition enters the segmentcontaining the catalyst a reaction will be triggered by such a catalyst.This catalytic segment may be extended into expansion zone if burning isexpected to continue into this zone (though this is undesirable fromefficiency standpoint)

Embodiments of the present invention are also provided in sealingsystems that may be used with engine embodiments of the presentinvention.

The function of a sealing system is to close the gap between any twomovably mounted mating parts; the gap is due to manufacturing precisionas well as due to differential thermal expansion between two matingparts. A sealing arrangement may be disposed on one a movable astationary component or on two movable sealing members in such a waythat seals a gap which exists between them.

A face seal seals a the gap that exists between any two flat matingsurfaces.

An apex seal seals the gap that exists between two mating surfaces, whenat least one of them is cylindrical.

A sealing members may include a rotor a gate a vane or a housing.

More generally, we note that a strip seal is typically comprised of astrip of a suitable low-friction, low-wear material, which may be metalor a polymer. The strip is located within the groove of suitable shapeand dimensions of one of the sealing members, while touching the surfaceof the other one of the sealing members, thus sealing the gap betweenthese two members. During the operation, the strip may be energized bythe fluid pressure, centrifugal force, spring or friction or all of theabove.

A roller seal is typically comprised of a roller that has a diameter ofat least several times larger than a gap. The roller is disposed betweensealing members, closing the gap. It rests on a flat surface of one ofthe sealing member and on cylindrical rotating surface of anothersealing member. The flat surface of the sealing member has the locatingtabs that limit the position of the roller in respect to such a sealingmember and allows roller only to rotate within the tabs. The roller isenergized by the fluid pressure.

Many conventional ways of sealing chambers within an engine existsincluding, a Wankel-like apex and face seals. The variations of a laterone are shown in FIG. 40. Additional seals were described in our patentapplications ##60/535,891, 60/900,182, 60/834,919, Ser. No. 11/832,483and PCT/US07/74980 and incorporated herein by reference. A number ofnovel configurations are described and claimed herein.

One embodiment of such a novel configuration provided in accordance withthe present invention is a bevel or wedge seal. A bevel (wedge) seal ispresented in FIGS. 40 b) and c). The sealing system consists of abeveled (in a cross section) seal with a matching groove in a rotor. Theseal is initially energized by a spring or a system of springs andduring the operation it is energized by one or more of the followingmechanisms: spring(s), gas pressure as done in Wankel-style face seals,and friction.

The frictional forces drug the seal along the face of the housing in thedirection opposite to the rotor's rotation. The seal, which generallyconforms to the rotor's edge profile, is non-circular; therefore, itcannot rotate within the groove. Instead, it “climbs up” on the bevelsurface of the groove toward the housing thus sealing the gap.

An optional elastomeric or resilient metal seal (C-, E-, U-, or anyother suitable cross section) may be used to enhance the sealingperformance.

Another embodiment of the present invention is providing in a floatingcover sealing system. A floating cover is shown in FIG. 41. It consistsof a cover that is not rigidly constrained in axial direction. Instead,it can “float” 0.001″ to 0.005″ or more above the housing. The rotor'sface is always in contact with this cover. The rotor may have a ridge,which actually contacts the cover, while the rest of the face isrecessed few thousands of an inch below the surface of the ridge. Theridge surface could be hardened or otherwise processes to reduce thewear and friction. Furthermore, the groove in the reach could be madethat will be oil-lubricated, which would further improve sealing.

To seal the floating cover includes a Wankel-style face seal(implemented as a strip of metal in a groove, energized by a spring).The diameter of this seal is ever slightly larger than the diameter ofthe rotor, so that when the rotor rotates, its circumference engageswith the seal.

The pressure due to action of the working medium upon the floating coverwill tend to move the floating cover axially away from the rotor's face.To counteract this, a fixed cover will be backs up the floating cover.To accommodate the axial movement of the floating cover and tocompensate for tolerance buildup and thermal expansion, the floatingcover will be supported by an oil film providing a reaction force equaland opposite to the axial force generated by pressurized gasses. Thisfilm will be of variable thickness, as one per revolution of the rotorit will be “re-supplied” from the slightly pressurized (10-20 psi)constant pressure oil supply. A valve, not shown in the figure, will cutoff the supply at the moment when pressure in the compression chamberstarts increasing. An oil film will be contained within the ring betweentwo sets of polymer seals located in the fixed cover.

An integrated rotor embodiment is shown in FIGS. 42 and 43. In thesefigures a gate having a rectangular cross section is used, but the samenotion applies toward any other suitable cross sections, mentionedthroughout this application, such as cylindrical segment, oval,compound, etc.

The rotor in the integrated rotor embodiment consists of the rotorproper and two cylindrical end plates, rigidly attached to the rotor.End plates, as show in, FIGS. 43 a) and b) contain seals, which may bepiston-like seals, as shown, face seals, or both. Since end plates areintegral with a rotor, there is no leak between rotor and end plates.

A rectangular cross-section gate is shown in FIG. 42 and FIGS. 43 b), c)and d), which has face seals that are in contact with the end plates.These face seals may be of a standard Wankel type and may be integratedwith the apex seals as shown in FIG. 43 c).

FIG. 44 shows a roller apex sealing system. It is applicable for usewith gates, vanes and rectangular pistons. It can be used to seal small(0.001″ to 0.050″ or above) gaps between two surfaces, one or both ofwhich may be movable. It consists of a roller in contact with these twosurfaces and it rolls on one surface while it slides on another. If itis used to seal a movable gate or vane, which is in periodicrelationship to a second sealing member, such as a rotor (i.e. itperiodically approaches and moves away from a rotor), then the gatewould need tabs, as shown in FIG. 44 a) or b) to contain the rollerwhile it is not in contact with the second sealing member. The gaspressure energizes and enhances this seal. Since one of the contactingsurfaces is in sliding motion with respect to the roller, it isbeneficial to supply it with a lubrication, which would also enableoil-supported hydrodynamic bearing surface.

Both rotors and gates (or vanes or pistons, etc.) require face seals toseal them with flat surfaces of engine covers or integrated rotors.Typical face seal requires anywhere from 0 to 0.010″ or more of travel.The main idea behind the split face seal system is to use the surfaceitself as a seal, instead of using a face seal. To accomplish this wesplit the surface that requires the face seal into two or more parts andsupply a high-temperature elastomeric or resilient metal member(mid-plane seal) between two or more parts.

To illustrate this approach FIG. 45 shows a split rotor face seal,consisting of two parts. These face seals are supported by ball bearingsto reduce the sliding friction face seals are energized by coil springsor wave washer spring (not shown). The mid-plane seal also provides someenergy to the face seals, but its main function is to seal the gap. Dueto the steep angle (˜12 deg), the vertical motion of the face seals,which is on the order of +/−0.005″ is translated into radial movement ofthe mid-plane seal on the order of less than 0.001″.

FIG. 43 c) shows a split gate face seal, which also consists of twoparts.

If the surface is split into many part, each requiring a very small gapon the order of 0.0001″ to be sealed, then instead of an elastomer orresilient metal oil pressurized to 10-15 psi may be used. The oil willnot flow through the 0.0001″ gap, thus, providing both the energy and asealing function.

A similar approach is used to provide an apex seal An apex seal may beprovided on a gate, vane, or piston being split into co-planar orco-radial elements that allow a relative motion between these elements.Each of these elements performs its original function and is energizedindependently of the other elements. FIG. 45 gives an example of thisapproach for vanes, which are split into two vanes, each providing thesame function, except that the apex sealing function is enhancedespecially if oil is used as it will collect between two vanes andprovide for an additional sealing. Each half-vane is energizedseparately, in this case by a centrifugal force. Two or more co-planaror co-radial vanes may be used.

A rotor face may also be enhanced by providing a rotor face with radialfeatures such as ridges (see i.e. FIG. 40 e)), dimples, strips, etc.radiated in a radial direction and disposed on a flat surface of therotor. These features reduce tangential flow of the fluid across theflat face surface of the rotor. These features may be used alone or incombination with conventional face seals and with seals offered in thisapplication.

This statement equally applies to all of the seals in this application.The seals, which are provided herein, may be used alone or incombination with each other and with other concepts presented herein.For example, the apex seal shown in FIG. 47, can double up as a catalystcarrier. It is formed by the thin plate (0.005″ to 0.025″ thick orabove) used as a catalytic trigger for a combustion reaction as wasdescribed above. Such a plate is naturally spring loaded as the platetends to stay flat and also due to centrifugal force, acting on the endsof the plate, which force the plate ends toward the housing walls, thusproviding the sealing. The edge of such a plate should only protrude afew thousands of an inch to cover for the manufacturing tolerances andthermal expansion of the rotor and the housing walls. The material forthe spring should be chosen to be harder than the walls to reduce thewearing of the edges. Additional features on the trailing edge of such aplate (not shown) may be used to provide a constant preload on the plateagainst the slot of the rotor in which the plate is placed. Similarlydesigned face seals are shown in FIGS. 47 b), e) and f). These seals arealso seated within machined groves. The depths of the grooves are thesame as thickness of the face seals, but the seals protrude from theface of the rotor 0.005 to 0.010″ due to the natural curvature of theseal. The sealing is done by the edge of the seal.

The gas pressure energizes and enhances this seal. Since one of thecontacting surfaces is in sliding motion with respect to the Roller, itis beneficial to supply it with a lubrication, which would also enableoil-supported hydrodynamic bearing surface.

Various embodiments of the present invention may be characterized by thepotential claims listed in the paragraphs following this paragraph (andbefore the actual claims provided at the end of this application). Thesepotential claims form a part of the written description of thisapplication. Accordingly, the following potential claims may bepresented as actual claims in later proceedings involving thisapplication or any application claiming priority based on thisapplication.

Potential claims:

1. A rotary engine comprising:

a. a housing having an intake port and an exhaust port;

b. a rotor rotatably mounted in the housing;

c. an annular segment of a hollow cylinder, mounted and driven to pivotin oscillatory fashion about a central axis, the segment having firstand second opposed ends forming a pair of connected gates, each endperiodically contacting the rotor, so as to define a volume within thehousing, the volume exhibiting a cycle during rotation of the rotorwherein, (i) while only the first end contacts the rotor, the volume isreduced in a compression portion of the cycle from a first quantity to asecond quantity, (ii) the volume is held substantially constant at thesecond quantity during a heat addition portion of the cycle, and (iii)while only the second end contacts the rotor, the volume is increased inan expansion portion of the cycle to a third quantity, the thirdquantity being larger than the first quantity.

2. An internal combustion engine comprising:

a housing having an intake port and an exhaust port;

at least three pistons movably mounted with respect to the housing, eachpiston formed of magnetic material;

a series of electromagnetic coils disposed around the housing, theelectromagnetic coils electronically controlled to exert forces on thepistons so as to implement a cycle wherein a volume is maintainedbetween the pistons and the housing, the volume exhibiting a cycleduring movement of the pistons wherein the volume is reduced in acompression portion of the cycle from a first quantity to a secondquantity, the volume is held substantially constant at the secondquantity during a heat addition portion of the cycle, and the volume isincreased in an expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.

3. A sealing system for a rotary engine comprising:

a. a plurality of grooves formed in an interior surface of a housingwall, and a spring-loaded sealing strip disposed in each of the grooves;

b. an orifice in the housing wall located between the grooves, theorifice coupled to an oil supply;

c. a floating cover disposed between the housing wall and a rotor of theengine, the floating cover having an inner face adjacent to a face ofthe rotor and an outer face adjacent to the interior surface of thehousing wall, the inner face of the floating cover including a groovehaving a diameter conforming generally to a diameter of the rotor, and aspring-loaded sealing strip located in the grove of the floating cover;

wherein the oil supply causes pressurized oil to apply an axial force tothe outer face of the floating cover in opposition to axial forces onthe inner face of the floating cover caused by a working medium of theengine so as to assist in sealing the engine.

4. An apex sealing system in a rotary engine for a first member that isone of a gate or a vane in relation to a second member, moving inrelation to the first member and at least periodically in contacttherewith at a contact region of the first member, the apex sealingsystem comprising:

a. a recess formed in the contact region of the first member;

b. a roller rotationally mounted in the recess, so that the rollercontacts the second member when the first member is in contact with thesecond member.

5. A sealing system for sealing, in a rotary engine, an interfacebetween a first member and second member with respect to which the firstmember moves, the first member presenting an edge, parallel to an axis,and in contact with the second member, the sealing system comprising:

a. at least one recess formed in the edge;

b. a plurality of axially adjacent strips, mounted in the at least onerecess, each strip being spring loaded, to maintain the strips inengagement with the second member.

6. A rotary engine comprising:

a. a housing having an intake port and an exhaust port;

b. a rotor rotatably mounted in the housing, the rotor having an axialchannel formed in an edge of the rotor, so that the channel lies axiallybetween two integrally formed end plates; and

c. at least one gate movably mounted with respect to the housing so asto be engageable with the axial channel and having a shape conformalwith the shape of the axial channel,

wherein during engagement of at least one gate with the rotor a volumeis maintained between a surface of the at least one gate, the rotor, andthe housing, the volume exhibiting a cycle during rotation of the rotorwherein the volume is reduced in a compression portion of the cycle froma first quantity to a second quantity, the volume is held substantiallyconstant at the second quantity during a heat addition portion of thecycle, and the volume is increased in an expansion portion of the cycleto a third quantity, the third quantity being larger than the firstquantity.

7. A sealing system for improving sealing in a rotary engine between afirst member that functions as one of a vane or gate, and capable ofmotion along an axis, and a second member moving with respect to thefirst member, the first member engageable against the second member at alimit of motion along the axis, the sealing system comprising:

a matched pair of components, the matched pair serving as the firstmember;

each one of the matched pair being mounted so as to be separatelymovable along the axis of movement of the first member;

so that each component may move differentially relative to the othercomponent to improve sealing at the limit of motion of the components.

8. An internal combustion engine comprising:

a. a bilateral piston, having an intake port and an exhaust port, andpair of opposed piston faces;

b. a housing, mounted concentrically outside of the piston and having apair of opposed internal contact faces, the housing moving in reciprocalmotion relative to the piston, along a longitudinal axis, each contactface coming into proximity of a corresponding one of the piston faces ofthe piston at a limit of the reciprocal motion; and

c. a piston actuator engaged with the piston relative to the housing,the piston actuator controlling the motion of the housing with respectto the piston so that a volume is defined between each piston face and acorresponding one of the contact faces, the volume exhibiting a cycleduring reciprocation of the housing relative to the piston wherein thevolume is reduced in a compression portion of the cycle from a firstquantity to a second quantity, the volume is held substantially constantat the second quantity during a heat addition portion of the cycle, andthe volume is increased in an expansion portion of the cycle to a thirdquantity, the third quantity being larger than the first quantity.

9. An internal combustion engine according to potential claim 8, whereinthe piston actuator is a cam having a shape that provides a dwell to thereciprocating motion of the housing relative to the piston.10. An internal combustion engine according to potential claim 8,wherein the piston actuator is an electromagnetic coil system.11. An internal combustion engine according to potential claim 8,wherein the piston and the housing are cylindrically shaped.12. An internal combustion engine comprising:

a cylinder having an intake port and an exhaust port;

a pair of pistons disposed for coordinated reciprocating motion in thecylinder, each of the pistons having a piston face, the pistons coupledto a rotational output in a manner to cause the pistons to define,within the cylinder and between the piston faces, a volume, the volumeexhibiting a cycle during reciprocation of the pistons wherein thevolume is reduced in a compression portion of the cycle from a firstquantity to a second quantity, the volume is held substantially constantat the second quantity during a heat addition portion of the cycle, andthe volume is increased in an expansion portion of the cycle to a thirdquantity, the third quantity being larger than the first quantity.

13. An internal combustion engine comprising:

a. a housing having an intake port and an exhaust port;

b. at least one piston movably mounted with respect to the housing; and

c. means for moving the piston through a cycle so that a volume ismaintained between the piston and the housing, the volume exhibiting acycle during movement of the piston wherein the volume is reduced in acompression portion of the cycle from a first quantity to a secondquantity, the volume is held substantially constant at the secondquantity during a heat addition portion of the cycle, and the volume isincreased in an expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.

14. An engine according to potential claim 13, wherein the pistonincludes a liquid.15. A rotary engine comprising:

a. an inner rotor, the inner rotor having a plurality N of lobes, and areceiving member, the inner rotor rotationally moving about an axis thatis displaced relative to an axis of the receiving member, the receivingmember having N+1 recesses for mating with successive lobes as the innerrotor rotates,

b. a drive for causing rotation of the inner rotor relative to thereceiving member, so that a volume is defined with respect to each lobeof the inner rotor and a corresponding recess of the receiving member,the volume exhibiting a cycle wherein the volume is reduced in acompression portion of the cycle from a first quantity to a secondquantity, the volume is held substantially constant at the secondquantity during a heat addition portion of the cycle, and the volume isincreased in an expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.

16. An engine according to potential claim 15, further comprising ahousing, the housing having and intake port and an exhaust port, whereinthe inner rotor rotates in a first direction relative to the housing andthe receiving member rotates in a second direction relative to thehousing.17. An engine according to potential claim 15, wherein the receivingmember is part of the housing, the housing having an intake port andexhaust port.

The embodiments of the invention described above are intended to bemerely exemplary; numerous variations and modifications will be apparentto those skilled in the art. All such variations and modifications areintended to be within the scope of the present invention as defined inany appended claims.

1. A rotary engine comprising: a. a housing having an intake port and anexhaust port; b. a rotor rotatably mounted in the housing; and c. twogates, each gate movably mounted with respect to the housing, so thateach gate is engaged at least periodically with the rotor, whereinduring engagement of at least one of the two gates with the rotor avolume is maintained between a surface of the at least one gate, therotor, and the housing, the volume exhibiting a cycle during rotation ofthe rotor wherein the volume is reduced in a compression portion of thecycle from a first quantity to a second quantity, the volume is heldsubstantially constant at the second quantity during a heat additionportion of the cycle, and the volume is increased in an expansionportion of the cycle to a third quantity, the third quantity beinglarger than the first quantity.
 2. A rotary engine according to claim 1,wherein the gates are slidably mounted with respect to the housing.
 3. Arotary engine according to claim 1, wherein the gates are pivotallymounted with respect to the housing.
 4. A rotary engine according toclaim 3, wherein the pivotally mounted gates form an external wall ofthe housing.
 5. A rotary engine according to claim 1, further comprisingtwo cams coupled to the gates, the cams rotated by a drive systemsynchronized with the rotation of the rotor.
 6. A rotary enginecomprising: a. a housing having at least one intake port and at leastone exhaust port; b. a plurality of rotors rotatably mounted in thehousing, each rotor coupled to one of the at least one intake port or toone of the at least one exhaust port; c. a plurality of gates, each gateassociated with, and in contact with, one of the rotors; d. at least onecombustion chamber, each of the at least one combustion chamber being incommunication with each rotor of a pair of the rotors, a first rotor ofthe pair of rotors being coupled to one of the at least one intake portand a second rotor of the pair of rotors being coupled to one of the atleast one exhaust port, the first and second rotors movingsynchronously, wherein (i) the first rotor and its gate define inrelation to the housing a compression volume exhibiting a compressionportion of an engine cycle during rotation of the first rotor, by whicha compressed volume of air is periodically coupled to the first rotor'scorresponding combustion chamber and (ii) the second rotor and its gatedefine in relation to the housing an expansion volume exhibiting anexpansion portion of the engine cycle during rotation of the secondrotor, by which a combusted mixture in the first rotor's combustionchamber is periodically coupled to the expansion volume; wherein thecompression volume is reduced in the compression portion of the cyclefrom a first quantity to a second quantity, a volume in which combustionoccurs is held substantially constant at the second quantity during aheat addition portion of the cycle, and the expansion volume isincreased in the expansion portion of the cycle to a third quantity, thethird quantity being larger than the first quantity.
 7. A rotary enginecomprising: a. a housing having an intake port and an exhaust port andan interior surface having a first arcuate segment characterized by aconstant radius of curvature and a second arcuate segment characterizedby a shape different from that of the first segment b. a rotor rotatablymounted concentrically within the first segment of the housing, anddisposed concentrically around a C-cam having a constant radiuscylindrical surface except where it has a recess; c. at least onecompression vane movably mounted in the rotor for contacting the C-camand defining a compression volume with the rotor, the C-cam, and thehousing; d. at least one expansion vane movably mounted in the rotor forcontacting the interior surface of the housing and defining an expansionvolume with the rotor and the housing; e. a combustion chamber, disposedin the rotor, associated with the at least one compression vane and theat least one expansion vane, wherein (i) the compression volume exhibitsa compression cycle during rotation of rotor, by which a compressedvolume of a working medium is periodically coupled to the combustionchamber and (ii) the expansion volume exhibits an expansion cycle duringrotation of the rotor, by which combustion products in the combustionchamber are periodically coupled to the expansion volume.
 8. A rotaryengine according to claim 7, further comprising a plurality ofcompression vanes, a plurality of expansion vanes, and a plurality ofcombustion chambers, each of the combustion chambers being associatedwith a corresponding compression vane and a corresponding expansionvane.
 9. A rotary engine according to claim 7, wherein the at least onecompression vane and the at least one expansion vane are mounted in therotor by one of a pivotal mount and a slidable mount.
 10. A rotaryengine according to claim 7, further comprising a plurality of C-ringsmounted in the rotor to provide sealing between the rotor and thehousing.
 11. A rotary engine according to claim 7, further comprising aplurality of grooves formed within the housing for guiding motion of thevanes.
 12. An internal combustion engine comprising: a housing having anintake port and an exhaust port; a low pressure chamber and a highpressure chamber disposed in the housing, the low pressure chamber beinglarger than the high pressure chamber, each chamber having anepitrochoid-shaped interior in which is disposed a three-apex rotor,rotationally mounted to move eccentrically within the correspondingchamber, to establish three cavities, which over an engine cycle, handlethe functions of intake, compression, intermediate, and expansion, threeof such functions being operative at any given time in each chamber;wherein (i) the cavity handling compression in the low pressure chamberis coupled to the cavity handling intake in the high pressure chamber;(ii) the cavity handling expansion in the high pressure chamber iscoupled to the cavity handling expansion in the low pressure chamber;and (iii) the cavity in the high pressure chamber handling theintermediate function handles heat addition so as to produce combustiontherein.
 13. A system for sealing a rotor of an internal combustionengine in relation to a housing, the rotor having an edge and a face,the system comprising: a. a groove formed in the face of the rotor,proximate to the edge and having a radially inward wall and a radiallyoutward wall, the groove having a bevel located in the radially outwardwall; and b. a sealing strip disposed in the grove and having, incontact with the groove, a conformal surface; wherein the strip isengaged in frictional contact against the housing, the housingpresenting to the sealing strip a substantially flat surface, thefriction tending to cause the strip to rotate slightly with respect tothe rotor and to move slightly axially in a direction out of the groove,so as to reduce any gap between the strip and the housing and so as toincrease sealing between the rotor and the housing.
 14. An improvedrotary internal combustion engine of the homogenous charge compressionignition type, causing combustion of a fuel-air mixture when a state ofthe mixture is transformed from subcritical to critical, wherein theimprovement comprises: a catalytic surface carried on a mechanicalsubstrate, the surface being normally concealed from the mixture; and atrigger for initiating combustion by causing the catalytic surface to beexposed to the mixture when the mixture is placed under minimum volumeconditions.
 15. A method according to claim 14, wherein the triggerincludes a catalytic surface placed directly on a rotor of the engine,in such a manner that it is exposed each time the rotor reaches aspecific angular extent in the cycle.
 16. A method according to claim14, wherein the trigger includes a catalytic surface placed in alocation of a housing of the engine, in such a manner that it is exposedeach time the rotor reaches a specific angular extent in the cycle. 17.A method of operating an HEHC engine in a manner permitting adjustmentof power output, the method comprising: in the heat addition portion ofthe cycle, adding fuel to the volume and causing combustion of the fuel,the amount of fuel added, when fuel is added, being substantiallyconstant over all cycles, so as to produce maximum power over each cyclewhen fuel is added; and controlling addition of fuel to occur only overa sufficient number of cycles per unit of time in order to produce adesired power output of the engine, and, for each cycle wherein additionof fuel is withheld, supplying heat during the heat addition portion ofthe cycle by heat transfer from at least one of (i) walls of the enginedirectly and (ii) a heat exchanger.
 18. A method according to claim 17,wherein the HEHC engine is an engine according to any of claims 1, 6, 7,and 12.